The Tanzanian army, with the support of the UNLF, drove the Ugandan forces out of Tanzania and began an invasion of Uganda. The Ugandan army offered little resistance and retreated steadily, spending much of its energies looting the countryside. Libya's Muammar al-Gaddafi sent 3,000 troops to support the Ugandan defense, but these troops found themselves fighting on the front lines, as Ugandan units in the rear commandeered their supply trucks to carry their plunder away. On 11 April 1979, Kampala fell to the invaders and Amin fled into exile, marking the first time in the post-colonial era that an African nation successfully invaded another.