On March 9, 1916, Germany declared war on Portugal, who earlier that year honored its alliance with Great Britain by seizing German ships anchored in Lisbon's harbor.
When World War I began in 1914, Portugal was a fledgling democratic republic, and newly elected president Manuel JosÉ de Arriaga was anxious about the security of Portugal's colonial holdings in Angola and Mozambique but desperate to remain neutral in the war.
In order to secure international support for its authority in Africa, Portugal begrudgingly entered the war on the side of Britain and the Allies. Its participation was at first limited to naval support, but by February of 1917, Portugal had 50,000 men stationed on the Western Front.
On March 13, 1781, the German-born English astronomer William Hershel discovers Uranus, the seventh planet from the sun. Herschel's discovery of a new planet was the first to be made in modern times, and also the first to be made by use of a telescope, which allowed Herschel to distinguish Uranus as a planet, not a star, as previous astronomers believed.