During the American Civil War (1861–1865), Washington, D.C., the capital city of the United States, was the center of the Union war effort, which rapidly turned it from a small city into a major capital with full civic infrastructure and strong defenses.

The shock of the Union defeat at the First Battle of Bull Run in July 1861, with demoralized troops wandering the streets of the capital, caused President Abraham Lincoln to order extensive fortifications and a large garrison. That required an influx of troops, military suppliers and building contractors, which would set up a new demand for accommodation, including military hospitals. The abolition of slavery in Washington in 1862 also attracted many freedmen to the city. Except for one attempted invasion by Confederate cavalry leader Jubal Early in 1864, the capital remained impregnable.

When Lincoln was assassinated in Ford's Theater in April 1865, thousands flocked into Washington to view the coffin, further raising the profile of the city. The new president, Andrew Johnson, wanted to dispel the funereal atmosphere and organized a program of victory parades, which revived public hopes for the future.
From the passage provided, extract the date when Lincoln was assasinated
Lincoln was assassinated in Ford's Theater in April 1865