The base was stormed by Taliban fighters last year, resulting in the deaths of two Marines and eight personnel. Fighters also destroyed of six U.S. fighter jets at Camp Bastion in the largest loss of Marine aircraft since the Vietnam war.
A four-month investigation concluded that Major General Charles Gurganus, the top Marine commander in the region at the time, and Major General Gregg Sturdevant, "did not take adequate force protection measures within the range of responses proportionate to the threat," the Marine Corps said in a statement.
The two "failed to exercise the level of judgment expected of commanders of their rank," said Commandant General James Amos.
Amos found Gurganus "made an error in judgment when conducting his risk assessment of the enemy's capabilities and intentions."
He also found Sturdevant, who commanded the aviation unit, failed to protect the airfield properly.
This is the first time since the Vietnam war that a general -- let alone two -- has been let go for negligence after an enemy attack. Amos asked both men to retire Monday, speaking personally with Gurganus at the Pentagon and by video conference with Sturdevant, who was abroad.
Both men accepted the requests and will submit their retirement letters accordingly.