April 6 in Military History

The Continental Navy squadron under Commodore Esek Hopkins, returning from a raid on the Bahamas, encountered HMS Glasgow off Block Island. The running gun battle was the young navy's first surface engagement against a Royal Navy warship and exposed serious shortcomings in American command and gunnery.

Confederate forces under General Albert Sidney Johnston launched a surprise dawn attack on Union troops at Pittsburg Landing near Shiloh Church, Tennessee. The ferocious two-day battle produced nearly 24,000 casualties, the bloodiest engagement in American history to that point.

Union forces cut off and overwhelmed roughly one-third of Lee's retreating army near Farmville, Virginia. Over 7,700 Confederates were captured, including six generals, prompting Lee to exclaim "My God, has the army been dissolved?"

U.S. Navy Commander Robert Peary announced that he had reached the North Pole after a five-year campaign of Arctic expeditions staged from the purpose-built ship SS Roosevelt. The expedition pioneered logistics and navigation techniques later applied to Navy polar operations and laid the groundwork for strategic Arctic access.

The House voted 373-50 to declare war on Germany, committing American industrial power and millions of fresh troops to World War I.

Germany launched simultaneous invasions of Yugoslavia and Greece. The Luftwaffe bombed Belgrade on Palm Sunday, killing thousands of civilians. Yugoslavia surrendered within 11 days; Greece fell by the end of April.

Japan launched approximately 355 kamikazes and 344 escort fighters against the Allied fleet off Okinawa, sinking the destroyers USS Bush and USS Colhoun and damaging 20 other vessels in the largest coordinated suicide air attack of the war.

The Imperial Japanese Navy's flagship Yamato, the largest battleship ever built, departed the Bungo Strait on a one-way mission to attack the American fleet off Okinawa. Escorted by a light cruiser and eight destroyers with fuel enough only for the outbound run, the task force was overwhelmed by U.S. carrier aircraft the following day.

The world's first commercial communications satellite, Intelsat I, was launched from Cape Kennedy aboard a Delta D rocket and placed in geostationary orbit. Although a commercial platform, Early Bird provided the U.S. military with the first reliable transatlantic satellite voice and data circuits used operationally.

Space Shuttle Challenger launched on STS-41C, carrying the crew that would conduct the first on-orbit satellite repair. Astronauts George Nelson and James van Hoften used the Canadarm and a Manned Maneuvering Unit to capture and service the ailing Solar Maximum Mission spacecraft, proving in-space repair was practical.

In response to the Assad regime's chemical weapons attack on Khan Shaykhun, the U.S. Navy launched 59 Tomahawk cruise missiles from the destroyers USS Porter and USS Ross at Syria's Al-Shayrat Air Base, the first direct American military action against the Assad government.