April 19: Easter (Eastern Christianity, 2009); Feast of Saint Alphege (Western Christianity) * 1713 – With no living male heirs, Holy Roman Emperor Charles VI issued the Pragmatic Sanction to ensure one of his daughters would inherit the Habsburg lands. * 1775 – The American Revolutionary War began with the Battles of Lexington and Concord in the British colony of Massachusetts. * 1943 – Nazi German troops entered the Warsaw Ghetto to round up the remaining Jews, sparking the first mass uprising in Poland against the Nazi occupation during the Holocaust. * 1971 – The first space station, Salyut 1, was launched from the Baikonur Cosmodrome near Tyuratam, Kazakh SSR, USSR. * 1995 – A car bomb was detonated in front of the Alfred P. Murrah Federal Building in Oklahoma City,