Victory is ours! DCist has finally hammered down precisely what was creating noises that sounded like pile driving around the District early this morning: a World War II Anti-Tank Gun. Yes, you read that correctly.

Utilizing blank rounds, the cannon — much like the one featured in the video at the above right (here’s another video) — was fired numerous times this morning by the Old Guard‘s Presidential Salute Battery. The blasts were part of the unit’s training in preparation for ceremonial support which they provide during services for officers at Arlington National Cemetery and when certain dignitaries visit the White House.

Major John Miller, spokesperson for the Old Guard, told DCist that during similar training last week, the unit received several complaints from residents of northern Arlington about the noise — so this week, they adjusted the aim of the gun to point toward the Potomac River, which, obviously, made the blasts much louder for those residing inside the District, especially in those neighborhoods closer to the waterfront. “We coordinated with Arlington National Cemetery and the Arlington County dispatcher to make sure it was a good time to fire,” Miller said, noting that the County dispatcher only received one complaint this morning.

“We want to be good neighbors, but they can’t do that training during the day,” said Miller. “[Early morning] is the only time we have to train.”