The gunshot that killed Lincoln came from John Wilkes Booth’s .44-caliber derringer as the president and his wife watched “Our American Cousin” at Ford’s Theatre.  At 7:22 the following morning, April 15, 1865, in the Petersen boarding house across from the theatre, the 16th president of the United States took his last breath, but not before making his mark in history. Who the Secretary of State Edwin M. Stanton called “the most perfect ruler of men the world has ever seen.” Ford’s Theatre is hosting a comprehensive series of Lincoln memorials, which it calls Ford’s 150: Remembering the Lincoln Assassination. The commemorations will be on Tuesday and Wednesday in Washington, D.C.…