Which battle, the costliest ever fought by the us army, started as a blitzkrieg from the ardennes to antwerp?

Battle of the Bulge

This was as a result of Hitler attempts to split the Allied armies in Northwest Europe through a surprise attack. He was successful in catching the American off guard. As the German forces drove deeper into the Ardennes in an attempt to secure vital bridgeheads, the Allied line took on the appearance of a large bulge hence the name.

b. they tried to evict the squatters from the area.

so sorry if wrong