History is made by ordinary people doing extraordinary things. The fact that often time's history doesn't record the heroics of these people doesn't alter that. The missions on 6 June range from:
1944 A.D.: Parachuting in behind the beaches of Normandy and linking up with the Resistance to insure the last 'good war' ends the way history records.
478 B.C.: At the Pythian Games in Greece in 478A.D., where art and war merge.
452 A.D.: A monster's lair in 452 A.D. where a man becomes the legend of Beowulf.
1843 A.D: At West Point, where a middling cadet, small in stature, named Ulysses S. Grant is trying to survive and graduate, with his curious brain that mixes war and art.
1998 A.D.: In a secret nuclear weapons depot in Pakistan, where the saber-rattling of nuclear tests is getting ready to escalate into Armageddon; a war to end all wars.
And, strangest of all, a mission thousands of years into pre-history, to the day Art is born.

While history doesn't record the heroics by the ordinary, there are those who do notice. And there are those who want to stop those ordinary people and change our history in order to create a time tsunami and wipe our present out of existence. It is up to the Time Patrol to send an agent back to six different years on the 6th of June and make sure that doesn't happen