<a href="https://en.wikipedia.org/wiki/Albert_Einstein" id="mw0Q" rel="mw:WikiLink" title="Albert Einstein">Albert Einstein</a> and <a href="https://en.wikipedia.org/wiki/Leo_Szilard" id="mw0g" rel="mw:WikiLink" title="Leo Szilard">Leo Szilard</a> write <a class="mw-redirect" href="https://en.wikipedia.org/wiki/Einstein–Szilárd_letter" id="mw0w" rel="mw:WikiLink" title="Einstein–Szilárd letter">a letter</a> to <a href="https://en.wikipedia.org/wiki/Franklin_D._Roosevelt" id="mw1A" rel="mw:WikiLink" title="Franklin D. Roosevelt">Franklin D. Roosevelt</a>, urging him to begin the <a href="https://en.wikipedia.org/wiki/Manhattan_Project" id="mw1Q" rel="mw:WikiLink" title="Manhattan Project">Manhattan Project</a> to develop a nuclear weapon.