Army 250th anniversary parade

The official focus of the parade is the commemoration of the U.S. Army's 250th anniversary. But critics say the president is using the military show of force to push a political agenda and celebrate his birthday, which happens to fall on the same date.

In a few days, the nation's capital will host its largest military parade in more than three decades. We look at some numbers behind the celebration and the key historical moments leading up to it.