The <a href="https://en.wikipedia.org/wiki/South_African_Defence_Force" id="mwARc" rel="mw:WikiLink" title="South African Defence Force">South African Defence Force</a> attacks a <a class="mw-redirect" href="https://en.wikipedia.org/wiki/South_West_Africa_People's_Organization" id="mwARg" rel="mw:WikiLink" title="South West Africa People's Organization">SWAPO</a> base at <a href="https://en.wikipedia.org/wiki/Cassinga" id="mwARk" rel="mw:WikiLink" title="Cassinga">Cassinga</a> in southern <a href="https://en.wikipedia.org/wiki/Angola" id="mwARo" rel="mw:WikiLink" title="Angola">Angola</a>, killing about 600 people.<sup about="#mwt130" class="mw-ref reference" data-mw='{"name":"ref","attrs":{},"body":{"id":"mw-reference-text-cite_note-21"}}' id="cite_ref-21" rel="dc:references" typeof="mw:Extension/ref"><a href="./May_4#cite_note-21" id="mwARs" style="counter-reset: mw-Ref 21;"><span class="mw-reflink-text" id="mwARw">[21]</span></a></sup>
<span class="mw-reference-text" id="mw-reference-text-cite_note-21"><cite about="#mwt127" class="citation web cs1" id="mwBmQ"><a class="external text" href="https://publicholidays.africa/namibia/cassinga-day/" id="mwBmU" rel="mw:ExtLink nofollow">"Cassinga Day 2021, 2022 and 2023 in Namibia"</a>. <i id="mwBmY">PublicHolidays.africa</i><span class="reference-accessdate" id="mwBmc">. Retrieved <span class="nowrap" id="mwBmg">January 18,</span> 2021</span>.</cite><span about="#mwt127" class="Z3988" id="mwBmk" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&amp;rft.genre=unknown&amp;rft.jtitle=PublicHolidays.africa&amp;rft.atitle=Cassinga+Day+2021%2C+2022+and+2023+in+Namibia&amp;rft_id=https%3A%2F%2Fpublicholidays.africa%2Fnamibia%2Fcassinga-day%2F&amp;rfr_id=info%3Asid%2Fen.wikipedia.org%3AMay+4"></span></span>