On this day in 1947, Jackie Robinson, age 28, becomes the first African-American player in Major League Baseball when he steps onto Ebbets Field in Brooklyn to compete for the Brooklyn Dodgers. Robinson broke the color barrier in a sport …

On this day, April 10, 1963, USS Thresher (SSN-593) began a series of sea trial exercises, accompanied by the submarine escort ship Skylark. The exercises were conducted at the end of a major ship overhaul performed at Portsmouth Naval Shipyard …