Emperor <a href="https://en.wikipedia.org/wiki/Diocletian" id="mwGw" rel="mw:WikiLink" title="Diocletian">Diocletian</a> and <a href="https://en.wikipedia.org/wiki/Maximian" id="mwHA" rel="mw:WikiLink" title="Maximian">Maximian</a> appoint <a href="https://en.wikipedia.org/wiki/Constantius_Chlorus" id="mwHQ" rel="mw:WikiLink" title="Constantius Chlorus">Constantius Chlorus</a> and <a href="https://en.wikipedia.org/wiki/Galerius" id="mwHg" rel="mw:WikiLink" title="Galerius">Galerius</a> as <a href="https://en.wikipedia.org/wiki/Caesar_(title)" id="mwHw" rel="mw:WikiLink" title="Caesar (title)">Caesars</a>. This is considered the beginning of the <a href="https://en.wikipedia.org/wiki/Tetrarchy" id="mwIA" rel="mw:WikiLink" title="Tetrarchy">Tetrarchy</a>, known as the <i id="mwIQ">Quattuor Principes Mundi</i> ("Four Rulers of the World").<sup about="#mwt20" class="mw-ref reference" data-mw='{"name":"ref","attrs":{},"body":{"id":"mw-reference-text-cite_note-2"}}' id="cite_ref-2" rel="dc:references" typeof="mw:Extension/ref"><a href="./March_1#cite_note-2" id="mwIg" style="counter-reset: mw-Ref 2;"><span class="mw-reflink-text" id="mwIw">[2]</span></a></sup>
<span class="mw-reference-text" id="mw-reference-text-cite_note-2"><cite about="#mwt17" class="citation book cs1" id="CITEREFBanchich2009">Banchich, Thomas Banchich M. (2009). <a class="external text" href="https://books.google.com/books?id=8_CBAgAAQBAJ" id="mwBsY" rel="mw:ExtLink nofollow"><i id="mwBsc">The History of Zonaras: From Alexander Severus to the Death of Theodosius the Great</i></a>. New York: Routledge. p.<span id="mwBsg" typeof="mw:Entity"> </span>137. <a class="mw-redirect" href="./ISBN_(identifier)" id="mwBsk" rel="mw:WikiLink" title="ISBN (identifier)">ISBN</a><span id="mwBso" typeof="mw:Entity"> </span><a href="./Special:BookSources/9780415299091" id="mwBss" rel="mw:WikiLink" title="Special:BookSources/9780415299091"><bdi id="mwBsw">9780415299091</bdi></a>.</cite><span about="#mwt17" class="Z3988" id="mwBs0" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Abook&amp;rft.genre=book&amp;rft.btitle=The+History+of+Zonaras%3A+From+Alexander+Severus+to+the+Death+of+Theodosius+the+Great&amp;rft.place=New+York&amp;rft.pages=137&amp;rft.pub=Routledge&amp;rft.date=2009&amp;rft.isbn=9780415299091&amp;rft.aulast=Banchich&amp;rft.aufirst=Thomas+Banchich+M.&amp;rft_id=https%3A%2F%2Fbooks.google.com%2Fbooks%3Fid%3D8_CBAgAAQBAJ&amp;rfr_id=info%3Asid%2Fen.wikipedia.org%3AMarch+1"></span></span>