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.

On March 12, 1930, Indian independence leader Mohandas Gandhi begins a defiant march to the sea in protest of the British monopoly on salt, his boldest act of civil disobedience yet against British rule in India.

Britain's Salt Acts prohibited Indians from collecting or selling salt, a staple in the Indian diet. Citizens were forced to buy the vital mineral from the British, who, in addition to exercising a monopoly over the manufacture and sale of salt, also exerted a heavy salt tax.

Although India's poor suffered most under the tax, Indians required salt. Defying the Salt Acts, Gandhi reasoned, would be an ingeniously simple way for many Indians to break a British law nonviolently.

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 this day in history in Russia, the February Revolution (known as such because of Russia's use of the Julian calendar) begins on this day in 1917, when riots and strikes over the scarcity of food erupt in Petrograd (now St. Petersburg).

Demonstrators clamoring for bread took to the streets of the Russian capital of Petrograd. Supported by 90,000 men and women on strike, the protesters clashed with police, refusing to leave the streets.

Three days after the riots began and Russian army troops were sent to quell the protests, the troops turned against the Czar and became part of the protest. The imperial government was forced to resign and Nicolas abdicated his throne, formally ending over four centuries of Czarist rule in Russia.

On this day in history, Nazi leader Adolf Hitler violates the Treaty of Versailles and the Locarno Pact by sending German military forces into the Rhineland, a demilitarized zone along the Rhine River in western Germany.

In 1935, Hitler unilaterally canceled the military clauses of the treaty and in March 1936 denounced the Locarno Pact and began remilitarizing of the Rhineland. Two years later, Nazi Germany burst out of its territories, absorbing Austria and portions of Czechoslovakia.

In 1939, Hitler invaded Poland, leading to the outbreak of World War II in Europe.

On this day in history, Michelangelo Buonarroti, the greatest of the Italian Renaissance artists, is born in the small village of Caprese on March 6, 1475.

The son of a government administrator, he grew up in Florence, a center of the early Renaissance movement, and became an artist's apprentice at age 13.

Michelangelo's impressive collection of work includes the Pieta (1498), David (1504), and The Creation of Adam (1508-1512). Michelangelo continued producing sculptures, frescoes, architectural designs and drawings until his death in 1564 at the age of 88.

On the cold, snowy night of March 5, 1770, a mob of American colonists gathers at the Customs House in Boston and begins taunting the British soldiers guarding the building in protest of unpopular taxation.

The protesters pelted British troops with snowballs until Private Hugh Montgomery was hit, causing him to discharge his rifle into the crowd. The other soldiers began firing as well, until five colonists lay dead or dying.

Crispus Attucks, Patrick Carr, Samuel Gray, Samuel Maverick, and James Caldwell died from their wounds, and their deaths are regarded by some historians as the first casualties of the American Revolutionary War.