This week we’re taking the measure of the mystery known as LBJ at the Selma moment: not the cinema bully caught dragging his heels in movie theaters this month in Ava DuVernay’s Selma, but the real bully who brought us both the Voting Rights Bill and the disastrous war in Vietnam.

We want to look at the big historical picture — and a strange coincidence. On March 7, 1965, black Southerners, organized by Martin Luther King, Jr. and the Southern Christian Leadership Conference, began a rolling series of marches to provoke an outrage and to raise the profile of the drive to vote.

Just a day later, on March 8, the first battalion of Marines landed at Da Nang, quietly announcing the beginning in earnest of the Vietnam war.

King, who had built a relationship with Johnson over the common cause of civil rights, once apologized to the President for seeming to recommend an American withdrawal in the press. But by 1967 King had grown revolted by the war. At the podium he began to offer a deep and stinging critique of war and of modern America itself. Johnson was furious.

It’s been 50 years since Johnson passed the pieces of legislation that would remake American society, 50 years since he started a war that would claim millions of Vietnamese lives. So it’s not just modern-day moviegoers and African-Americans — we’re all figuring out the legacy of the imperial, irascible Johnson, at home and abroad.