<a href="https://en.wikipedia.org/wiki/Operation_Grapple#Grapple_X_(1_test)" id="mw5g" rel="mw:WikiLink" title="Operation Grapple">Operation Grapple X, Round C1</a>: The United Kingdom conducts its first successful <a class="mw-redirect" href="https://en.wikipedia.org/wiki/Hydrogen_bomb" id="mw5w" rel="mw:WikiLink" title="Hydrogen bomb">hydrogen bomb</a> test over <a href="https://en.wikipedia.org/wiki/Kiritimati" id="mw6A" rel="mw:WikiLink" title="Kiritimati">Kiritimati</a> in the Pacific.