On this day, April 4

1841 President William Henry Harrison succumbed to pneumonia one month after his inaugural, becoming the first U.S. chief executive to die in office; John Tyler became the first vice president to assume the office of president after such a death.

1865 President Abraham Lincoln, accompanied by his son Tad, visited the vanquished Confederate capital of Richmond, Va., where he was greeted by a crowd that included former slaves.

1949 Twelve nations, including the United States, signed the North Atlantic Treaty in Washington, D.C.

1968 Civil rights leader Martin Luther King Jr., 39, was shot and killed while standing on a balcony of the Lorraine Motel in Memphis, Tenn.; his slaying was followed by a wave of rioting (Washington, D.C., Baltimore and Chicago were among cities particularly hard hit). James Earl Ray later pleaded guilty to assassinating King, then spent the rest of his life claiming he’d been the victim of a setup.

1974 Hank Aaron of the Atlanta Braves tied Babe Ruth’s home-run record by hitting his 714th round-tripper in Cincinnati.

1991 Sen. John Heinz, R-Pa., and six other people, including two children, were killed when a helicopter collided with Heinz’s plane over a schoolyard in Merion, Pa.

2011 Yielding to political opposition, the Obama administration gave up on trying avowed Sept. 11 mastermind Khalid Sheik Mohammed and four alleged co-conspirators in civilian federal courts and said it would prosecute them instead before military commissions.

2015 In North Charleston, S.C., Walter Scott, a 50-year-old Black motorist, was shot to death while running away from a traffic stop; Officer Michael Thomas Slager, seen in a cellphone video opening fire at Scott, was charged with murder. (The charge, which lingered after a first state trial ended in a mistrial, was dropped as part of a deal under which Slager pleaded guilty to a federal civil rights violation; he was sentenced to 20 years in prison.)

2018 Saying the situation had reached “a Lindsay point of crisis,” President Donald Trump signed a proclamation directing the deployment of the National Guard to the U.S.

Mexico border to fight illegal immigration.

Today’s birthdays: Recording executive

Clive Davis, 92. Author Kitty Kelley, 82. Actor Craig T. Nelson, 80. Actor Christine

Lahti, 74. Country singer Steve Gatlin, 73.

Actor Mary-Margaret Humes, 70. Writerproducer David E. Kelley, 68. Actor Constance Shulman, 66. Actor Phil Morris, 65.

Actor Lorraine Toussaint, 64. Actor Hugo Weaving, 64. Rock musician Craig Adams

(The Cult), 62. Talk show host/comic

Graham Norton, 61. Actor David Cross,

60. Actor Robert Downey Jr., 59. Actor

Nancy McKeon, 58. Actor Barry Pepper,

54. Country singer Clay Davidson, 53.