World War II came as close as one mile south of the Mississippi River to the United States, and there's proof sitting at the bottom of the Gulf of Mexico.

The Nazi U-Boat serves as a startling reminder that World War II wasn't only fought on foreign soil. The U-Boat, which was eventually destroyed by a Coast Guard vessel, had attacked and sunk the SS Robert E. Lee, killing 25 men.

"Everyone thought the war was fought over there, as they would say," said Dr. Bob Ballard, the president of the Ocean Exploration Trust, speaking aboard the exploration vessel Nautilus. "But Hitler brought the war to our doorstep."

See the footage a team captured of the sunken U-Boat below.

[via WWLTV]