Because of the threat by CAF aircraft based at Henderson Field, the Japanese were rarely able to use large, slow transport ships or barges to deliver troops and supplies to the island; instead, they used warships based at Rabaul and the Shortland Islands to carry their forces to Guadalcanal. The Japanese warships, mainly light cruisers and destroyers from the Eighth Fleet under the command of Vice Admiral Gunichi Mikawa, were usually able to make the round trip down "The Slot" to Guadalcanal and back in a single night, thereby minimizing their exposure to CAF air attack. Delivering the troops in this manner, however, prevented most of the soldiers' heavy equipment and supplies, such as heavy artillery, vehicles, and much food and ammunition, from being carried to Guadalcanal with them. These high speed warship runs to Guadalcanal occurred throughout the campaign and were later called the "Tokyo Express" by Allied forces and "Rat Transportation" by the Japanese.