Diocletian | Biography, Empire, Definition, Persecution, & Reign

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border-right-sm border-left-sm open"> <div class="drawer d-flex flex-column open"> <div class="left-rail-section-content"> <div class="topic-left-rail-header text-truncate bg-gray-50 position-relative text-right d-flex align-items-center"> <div class="tlr-title px-20 py-15 text-left"> <em class="material-icons text-gray-400 d-lg-none" data-icon="toc"></em> <a class="font-serif font-weight-bold text-black link-blue" href="https://www.britannica.com/biography/Diocletian">Diocletian</a> </div> <button aria-label="Close" class="js-sections-close-button btn-link btn-sm btn d-lg-none position-absolute top-0 p-10 right-0" > <em class="material-icons font-26" data-icon="close"></em> </button> </div> <div class="section-content pl-10 pr-20 pl-sm-50 pr-sm-60 pl-lg-5 pr-lg-10 pt-10 pt-lg-0 bg-gray-50 clear-catfish-ad"> <div class="toc mb-20"> <div class="font-serif font-14 font-weight-bold mx-15 mb-15 mt-20"> Table of Contents </div> <ul class="list-unstyled my-0" data-level="h1"><li 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align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/biography/Diocletian/Domestic-reforms">Domestic reforms</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref1832"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/biography/Diocletian/Domestic-reforms#ref1832">Persecution of Christians</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li><li data-target="#ref1833"><div class="d-flex align-items-center"><div class="ml-25"></div><a class="w-100 link-gray-900" href="/biography/Diocletian/Domestic-reforms#ref1833">Legacy</a></div><div class="ml-40 toc-drawer sub-toc-drawer"></div></li></ul> <a class="toc-extra-link link-gray-900" href="https://www.britannica.com/biography/Diocletian/additional-info">References & Edit History</a> <a class="toc-extra-link link-gray-900" href="/facts/Diocletian">Quick Facts & Related Topics</a> </div> <div class="tlr-media-slider 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src="https://cdn.britannica.com/23/59323-004-9DDEEFAC/Statue-Diocletian-tetrarchy-red-porphyry-ce-Venice-c-300-ce.jpg" alt="Diocletian's tetrarchy" height="50" /> </a> </div> <button disabled class="prev-button js-prev-button position-absolute btn btn-circle shadow btn-blue " aria-label="Previous"> <span class="material-icons md-24" data-icon="keyboard_arrow_left"></span> </button> <button disabled class="next-button js-next-button position-absolute btn btn-circle shadow btn-blue " aria-label="Next"> <span class="material-icons md-24" data-icon="keyboard_arrow_right"></span> </button> </div> </div> <div class="mb-30 tlr-student-links"> <div class="text-gray-900 p-5 font-serif font-14 font-weight-bold mx-10 mb-10"> For Students </div> <div class="imagelink-with-image-on-the-side card card-horizontal tlr-img-with-side-link ml-15 link-gray-900 mb-10" > <div class="position-relative card-media" style="flex: 0;"> <a class="ilf-image position-relative" href="/summary/Diocletian"> <img 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Author of <i>Destin de Rome </i>and others.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link gtm-byline font-12 byline-contributor text-decoration-underline"> Jean Cousin</span></div> <div class="font-serif font-12 text-gray-700"> <span class="qa-fact-checked-by">Fact-checked by</span> <div class="editor-popover popover p-0"> <a class="d-block p-20 font-12" href="/editor/The-Editors-of-Encyclopaedia-Britannica/4419" > <div class="editor-title font-16 font-weight-bold">The Editors of Encyclopaedia Britannica</div> <div class="editor-description font-12 font-serif mt-5 text-black">Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree. They write new content and verify and edit content received from contributors.</div> </a> <div data-popper-arrow></div> </div> <span class="btn btn-link editor-link p-0 qa-byline-link font-12 "> The Editors of Encyclopaedia Britannica</span></div> <div class="last-updated font-12 font-serif"> <span class="text-gray-700"> Last Updated: <time datetime="2024-10-25T00:00:00CDT" >Oct 25, 2024</time> •</span> <a class="byline-edit-history" href="https://www.britannica.com/biography/Diocletian/additional-info#history" rel="nofollow">Article History</a> </div></div> </div> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button d-none d-sm-block js-sections-inline-button module-spacing btn d-lg-none"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <div class="d-flex d-sm-none flex-row"> <button class="d-flex d-lg-none btn btn-outline-blue border rounded-sm shadow-sm mobile-toc-button gtm-mobile-toc-inline-button js-sections-inline-button module-spacing"> <em class="material-icons mr-5 ml-n10 my-n5 md-icon" data-icon="toc"></em> Table of Contents </button> <button class="ai-ask-button btn border-2 ai-ask-button btn border-2 module-spacing btn-sm js-inline-ai-ask-button btn-outline-red-400 border-red-400 p-10 ml-5"> Ask the Chatbot a Question </button> </div> <div class="js-qf-module qf-module px-40 px-sm-20 py-15 mx-auto module-spacing font-14 bg-gray-50 rounded"> <div class="qf-title font-weight-bold font-14 mb-10 text-center"> Quick Facts</div> <div class="facts-list mt-10"> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Latin in full: </dt> <dd>Gaius Aurelius Valerius Diocletianus</dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Original name: </dt> <dd>Diocles</dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Born: </dt> <dd>245 <span class="text-smallcaps">ce</span>, Salonae?, Dalmatia [now Solin, Croatia]</dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Died: </dt> <dd>316, Salonae (aged 71)</dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class=""> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Also Known As: </dt> <dd>Diocles</dd> <dd>Gaius Aurelius Valerius Diocletianus</dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> </div> <div class="facts-item-none d-none"> <div class="js-fact mb-10 line-clamp clamp-3"> <dl> <dt>Title / Office: </dt> <dd><a href="/topic/emperor-title">emperor (284-305)</a>, <a href="/place/Roman-Empire">Roman Empire</a></dd> </dl> <button class="js-more-btn d-none btn btn-unstyled font-12 bg-gray-50" aria-label="Toggle more/less fact data"> <em class="js-content link-blue">(Show more)</em> </button> </div> <div class="text-center"> <a class="btn btn-sm btn-link p-0" href="/facts/Diocletian"> See all related content </a> </div> </div> </div> <button class="facts-list-show-more-btn mt-15 p-0 mx-auto btn font-14 d-block font-weight-normal"> <span class="material-icons" data-icon="expand_more"></span> <span class="show-more-label">Show More</span> </button> </div><script type="application/ld+json"> { "@context": "https://schema.org", "@type": "FAQPage", "mainEntity": [ { "@type" : "Question", "name" : "<div>Why is Diocletian important?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "As Roman emperor for more than 20 years (284\u2013305 CE), Diocletian brought stability, security, and efficient government to the Roman state after nearly half a century of chaos. He instituted lasting administrative, military, and financial reforms and introduced a short-lived system of power sharing between four rulers, two augusti and two caesars (the tetrarchy)." } } , { "@type" : "Question", "name" : "<div>What was Diocletian\u2019s religion?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "Diocletian was an adherent of the traditional <a href=\"https:\/\/www.britannica.com\/topic\/Roman-religion\">Roman religion<\/a> involving worship of the pantheon of deities including Jove (<a href=\"https:\/\/www.britannica.com\/topic\/Jupiter-Roman-god\">Jupiter<\/a>), <a href=\"https:\/\/www.britannica.com\/topic\/Mars-Roman-god\">Mars<\/a>, <a href=\"https:\/\/www.britannica.com\/topic\/Apollo-Greek-mythology\">Apollo<\/a>, and others. Like his predecessors, Diocletian promoted the cult of the emperor but also explicitly associated himself and his co-augustus, <a href=\"https:\/\/www.britannica.com\/biography\/Maximian\">Maximian<\/a>, with Jove and <a href=\"https:\/\/www.britannica.com\/topic\/Heracles\">Hercules<\/a>, respectively. " } } , { "@type" : "Question", "name" : "<div>What did Diocletian do to Christians?<\/div><em><\/em>", "acceptedAnswer" : { "@type" : "Answer", "text" : "At the urging of the caesar <a href=\"https:\/\/www.britannica.com\/biography\/Galerius\">Galerius<\/a>, in 303 Diocletian began the last major persecution of Christians in the Roman Empire, resulting in the destruction of churches and the torture and execution of <a href=\"https:\/\/www.britannica.com\/topic\/Christianity\">Christians<\/a> who refused to sacrifice to the Roman gods. Galerius, who succeeded Diocletian as augustus in 305, continued the persecution until 311." } } ] } </script> <div class="top-questions qa-accordion d-flex flex-column module-spacing"><div class="font-weight-bold font-14 mb-5"> Top Questions </div><div id="intent-accordion" class="md-intent-accordion"><div class="top-question bg-gray-50 rounded" data-value="1"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>Why is Diocletian important?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p>As Roman emperor for more than 20 years (284–305 CE), Diocletian brought stability, security, and efficient government to the Roman state after nearly half a century of chaos. He instituted lasting administrative, military, and financial reforms and introduced a short-lived system of power sharing between four rulers, two augusti and two caesars (the tetrarchy).</p></div></div></div><div class="top-question bg-gray-50 rounded" data-value="2"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>What was Diocletian’s religion?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p>Diocletian was an adherent of the traditional <a href="https://www.britannica.com/topic/Roman-religion" class="md-crosslink " data-show-preview="true">Roman religion</a> involving worship of the pantheon of deities including Jove (<a href="https://www.britannica.com/topic/Jupiter-Roman-god" class="md-crosslink " data-show-preview="true">Jupiter</a>), <a href="https://www.britannica.com/topic/Mars-Roman-god" class="md-crosslink " data-show-preview="true">Mars</a>, <a href="https://www.britannica.com/topic/Apollo-Greek-mythology" class="md-crosslink " data-show-preview="true">Apollo</a>, and others. Like his predecessors, Diocletian promoted the cult of the emperor but also explicitly associated himself and his co-augustus, <a href="https://www.britannica.com/biography/Maximian" class="md-crosslink " data-show-preview="true">Maximian</a>, with Jove and <a href="https://www.britannica.com/topic/Heracles" class="md-crosslink " data-show-preview="true">Hercules</a>, respectively. </p></div></div></div><div class="top-question bg-gray-50 rounded" data-value="3"><h3 class="accordion--question font-14 font-weight-normal cursor-pointer rounded"><div class="pe-none d-flex justify-content-between align-items-center"><div>What did Diocletian do to Christians?</div><em class="material-icons" data-icon="expand_more"></em></div></h3><div class="accordion--answer hidden p-15 pt-5 font-16 mb-5"><div class="accordion--answer-copy"><p>At the urging of the caesar <a href="https://www.britannica.com/biography/Galerius" class="md-crosslink " data-show-preview="true">Galerius</a>, in 303 Diocletian began the last major persecution of Christians in the Roman Empire, resulting in the destruction of churches and the torture and execution of <a href="https://www.britannica.com/topic/Christianity" class="md-crosslink " data-show-preview="true">Christians</a> who refused to sacrifice to the Roman gods. Galerius, who succeeded Diocletian as augustus in 305, continued the persecution until 311.</p></div></div></div></div></div><span class="marker before-article"></span><section data-level="1" id="ref1"><span class="marker PREMOD1 mod-inline"></span><p class="topic-paragraph"><strong><span id="ref216282"></span>Diocletian</strong> (born 245 <span class="text-smallcaps">ce</span>, Salonae?, Dalmatia [now Solin, Croatia]—died 316, Salonae) was a <span id="ref216283"></span><a href="https://www.britannica.com/place/ancient-Rome" class="md-crosslink " data-show-preview="true">Roman</a> <a href="https://www.britannica.com/topic/emperor-title" class="md-crosslink autoxref " data-show-preview="true">emperor</a> (284–305 <span class="text-smallcaps">ce</span>) who restored efficient government to the <a href="https://www.britannica.com/place/Roman-Empire" class="md-crosslink " data-show-preview="true">empire</a> after the near <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="anarchy" href="https://www.merriam-webster.com/dictionary/anarchy" data-type="MW">anarchy</a> of the 3rd century. His reorganization of the fiscal, administrative, and <a href="https://www.britannica.com/topic/armed-force" class="md-crosslink autoxref " data-show-preview="true">military</a> machinery of the empire laid the foundation for the <a href="https://www.britannica.com/place/Byzantine-Empire" class="md-crosslink " data-show-preview="true">Byzantine Empire</a> in the East and temporarily shored up the decaying empire in the West. The last major persecution of <a href="https://www.britannica.com/topic/Christianity" class="md-crosslink " data-show-preview="true">Christians</a> occurred during his reign.</p><span class="marker MOD1 mod-inline"></span></section> <span class="marker h2"></span><section data-level="1" id="ref1828"><h2 class="h1">Life</h2> <span class="marker PREMOD2 mod-inline"></span><div class="assemblies"><div class="w-100"><figure class="md-assembly m-0 mb-md-0 card card-borderless print-false" data-assembly-id="154748" data-asm-type="image"><div class="md-assembly-wrapper card-media " data-type="image"><a href="https://cdn.britannica.com/69/146769-050-AC22F925/Gold-coin-emperor-Roman-Diocletian.jpg" class="gtm-assembly-link position-relative d-flex align-items-center justify-content-center media-overlay-link card-media" data-href="/media/1/164042/154748"><picture><source media="(min-width: 680px)" srcset="https://cdn.britannica.com/69/146769-050-AC22F925/Gold-coin-emperor-Roman-Diocletian.jpg?w=300"><img src="https://cdn.britannica.com/69/146769-050-AC22F925/Gold-coin-emperor-Roman-Diocletian.jpg?w=300" alt="Diocletian" data-width="1540" data-height="1600" loading="eager"></picture><button class="magnifying-glass btn btn-circle position-absolute shadow btn-white top-10 right-10" aria-label="Zoom in"><em class="material-icons link-blue" data-icon="zoom_in"></em></button></a></div><figcaption class="card-body"><div class="md-assembly-caption text-muted font-14 font-serif line-clamp"><span><a class="gtm-assembly-link md-assembly-title font-weight-bold d-inline font-sans-serif mr-5 media-overlay-link" href="https://cdn.britannica.com/69/146769-050-AC22F925/Gold-coin-emperor-Roman-Diocletian.jpg" data-href="/media/1/164042/154748">Diocletian</a><span>Gold coin depicting the Roman emperor Diocletian.</span><button class="js-more-btn d-none btn btn-unstyled font-12 bg-white js-content" aria-label="Toggle more/less fact data"><span class="link-blue">(more)</span></button></span></div></figcaption></figure></div></div><p class="topic-paragraph">Diocletian’s biography has been obscured by <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="legends" href="https://www.merriam-webster.com/dictionary/legends" data-type="MW">legends</a>, <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="rhetoric" href="https://www.merriam-webster.com/dictionary/rhetoric" data-type="MW">rhetoric</a>, the dubiousness of documents, and the hostility of his adversaries. Little is known of his origins. His father was a scribe or the emancipated slave of a senator called Anullinus. Diocletian’s complete name, found in official inscriptions, is given as Gaius Aurelius Valerius Diocletianus. He received the name Diocles first, then the name Valerius, after the name of his daughter, Valeria, who married <a href="https://www.britannica.com/biography/Galerius" class="md-crosslink " data-show-preview="true">Galerius</a> in 293. The gens name Aurelius did not appear until March 1, 286—that is, until after his accession. Nothing is known of his wife, Prisca, other than what the contemporary Latin Christian writer <span id="ref216284"></span><a href="https://www.britannica.com/biography/Lactantius" class="md-crosslink " data-show-preview="true">Lactantius</a> Firmianus says in his <em>De mortibus persecutorum</em>, which is of debatable <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="veracity" href="https://www.merriam-webster.com/dictionary/veracity" data-type="MW">veracity</a>. Diocles, having adopted the name Diocletianus, entered <a href="https://www.britannica.com/topic/history" class="md-crosslink autoxref " data-show-preview="true">history</a> like so many of those emperors who emerged from the shadows through force of arms, brought to power by the army. What is known of his appearance is based on coin effigies and on sculptures. From these it appears that he was tall and thin, with a large forehead, a short, strong nose, a hard mouth, and a determined chin.</p><span class="marker MOD2 mod-inline"></span></section> <span class="marker h3"></span><section data-level="1" id="ref1829"><h2 class="h1">Rise to power</h2> <span class="marker PREMOD3 mod-inline"></span><p class="topic-paragraph">Up to the time of his accession, Diocletian had lived most of his life in military camps. These may have been either in <a href="https://www.britannica.com/place/Gaul-ancient-region-Europe" class="md-crosslink " data-show-preview="true">Gaul</a>, as reported in the <em><span id="ref216285"></span><a href="https://www.britannica.com/topic/Augustan-History" class="md-crosslink " data-show-preview="true">Historia Augusta</a>,</em> or in <a href="https://www.britannica.com/place/Moesia" class="md-crosslink " data-show-preview="true">Moesia</a>. Or he may have been a member of the Roman emperor <span id="ref216286"></span><a href="https://www.britannica.com/biography/Carinus" class="md-crosslink " data-show-preview="true">Carinus</a>’s bodyguard. The only definite fact known about Diocletian during this period is that he was among those army chiefs whom Carinus gathered, together with the Illyrians, to fight against the Persians. In 284, during that campaign, <span id="ref216287"></span><a href="https://www.britannica.com/biography/Numerian" class="md-crosslink " data-show-preview="true">Numerian</a>, Carinus’s brother and coemperor, was found dead in his <a class="md-dictionary-link md-dictionary-tt-off eb" data-term="litter" href="https://www.britannica.com/dictionary/litter" data-type="EB">litter</a>, and his adoptive father, the <a href="https://www.britannica.com/topic/Praetorian-Guard" class="md-crosslink " data-show-preview="true">praetorian</a> prefect <span id="ref216288"></span><a href="https://www.britannica.com/biography/Aper" class="md-crosslink ">Aper</a>, was accused of having killed him in order to seize power. When Diocletian, acclaimed as emperor by his soldiers, appeared for the first time in public dressed in the imperial purple, he declared himself innocent of Numerian’s murder. He designated Aper as the criminal and killed him personally. Here again, rhetoric has obscured the real events. Aper’s guilt was accepted by contemporaries, but it was also true that a prediction had been made to Diocletian previously, telling him that he would become emperor on the day he killed a <a href="https://www.britannica.com/animal/boar-mammal" class="md-crosslink " data-show-preview="true">boar</a> (Latin: <em>aper</em>). And it was true, too, that he did not wish to wait much longer for the boar to come. In reality, Numerian had died either a natural death or from a stroke of <a href="https://www.britannica.com/science/lightning-meteorology" class="md-crosslink " data-show-preview="true">lightning</a>. With the death of Aper, however, Diocletian was relieved of an eventual competitor and, retroactively, his act had been granted sacred meaning.</p><div class="one-good-fact-module"> </div><span class="marker MOD3 mod-inline"></span> <span class="marker PREMOD4 mod-inline"></span><p class="topic-paragraph">Acclaimed emperor on November 17, 284, Diocletian possessed real power only in those countries that were dominated by his army (i.e., in <a href="https://www.britannica.com/place/Anatolia" class="md-crosslink autoxref " data-show-preview="true">Asia Minor</a> and possibly <a href="https://www.britannica.com/place/Syria" class="md-crosslink " data-show-preview="true">Syria</a>). The rest of the empire was obedient to Numerian’s brother Carinus. After having put down a revolt by Julianus, a troop commander in <a href="https://www.britannica.com/place/Pannonia" class="md-crosslink " data-show-preview="true">Pannonia</a>, whom he attacked and killed near <a href="https://www.britannica.com/place/Verona-Italy" class="md-crosslink " data-show-preview="true">Verona</a>, Carinus proceeded to attack Diocletian. An indecisive battle near the <a class="md-dictionary-link md-dictionary-tt-off mw" data-term="confluence" href="https://www.merriam-webster.com/dictionary/confluence" data-type="MW">confluence</a> of the Margus (modern <a href="https://www.britannica.com/place/Morava-River-Serbia" class="md-crosslink " data-show-preview="true">Morava</a>) and <a href="https://www.britannica.com/place/Danube-River" class="md-crosslink " data-show-preview="true">Danube</a> rivers, not far from present-day <a href="https://www.britannica.com/place/Belgrade" class="md-crosslink " data-show-preview="true">Belgrade</a>, would have been a defeat for Diocletian had Carinus not been assassinated by a group of soldiers. Thus, in midsummer of 285, Diocletian became master of the empire.</p><span class="marker MOD4 mod-inline"></span></section> <span class="marker end-of-content"></span><span class="marker after-article"></span></div> <div id="chatbot-root"></div> </div> </div> </div> <div class="ai-dialog-placeholder"></div> </div> </div> <aside class="col-md-da-320"></aside> </div> </div> </div> </div> </article></div> </div></div> </div> </main> <div id="md-footer"></div> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-5W6NC8" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript> <script type="text/javascript" id="_informizely_script_tag"> var IzWidget = IzWidget || {}; (function (d) { var scriptElement = d.createElement('script'); scriptElement.type = 'text/javascript'; scriptElement.async = true; scriptElement.src = "https://insitez.blob.core.windows.net/site/f780f33e-a610-4ac2-af81-3eb184037547.js"; var node = d.getElementById('_informizely_script_tag'); node.parentNode.insertBefore(scriptElement, node); } )(document); </script>  <script> window.ap3c = window.ap3c || {}; var ap3c = window.ap3c; ap3c.cmd = ap3c.cmd || []; ap3c.cmd.push(function() { ap3c.init('ZO4siT4cLwnykPnzZWJtd3Byb2Q', 'https://engage.email.britannica.com/'); ap3c.track({v: 0}); }); ap3c.activity = function(act) { ap3c.act = (ap3c.act || []); ap3c.act.push(act); }; var s, t; s = document.createElement('script'); s.type = 'text/javascript'; s.src = "https://engage.email.britannica.com/app.js"; t = document.getElementsByTagName('script')[0]; t.parentNode.insertBefore(s, t); </script> <script class="marketing-page-info" type="application/json"> {"pageType":"Topic","templateName":"DESKTOP","pageNumber":1,"pagesTotal":3,"pageId":164042,"pageLength":661,"initialLoad":true,"lastPageOfScroll":false} </script> <script class="marketing-content-info" type="application/json"> [] </script> <script src="https://cdn.britannica.com/mendel-resources/3-130/js/libs/jquery-3.5.0.min.js?v=3.130.14"></script> <script type="text/javascript" data-type="Init Mendel Code Splitting"> (function() { $.ajax({ dataType: 'script', cache: true, url: 'https://cdn.britannica.com/mendel-resources/3-130/dist/topic-page.js?v=3.130.14' }); })(); </script> <script class="analytics-metadata" type="application/json"> {"leg":"B","adLeg":"B","userType":"ANONYMOUS","pageType":"Topic","pageSubtype":null,"articleTemplateType":"BIO_PAGINATED","gisted":false,"pageNumber":1,"hasSummarizeButton":false,"hasAskButton":false} </script> <script type="text/javascript"> EBStat={accountId:-1,hostnameOverride:'webstats.eb.com',domain:'www.britannica.com', json:''}; </script> <script type="text/javascript"> ( function() { $.ajax( { dataType: 'script', cache: true, url: '//www.britannica.com/webstats/mendelstats.js?v=1' } ) .done( function() { try {writeStat(null,EBStat);} catch(err){} } ); })(); </script> <div id="bc-fixed-dialogue"></div> </body> </html>

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Diocletian | Biography, Empire, Definition, Persecution, & Reign | Britannica