Passage: Underestimating the strength of Allied forces on Guadalcanal, which at that time numbered about 11,000 personnel, Ichiki's unit conducted a nighttime frontal assault on Marine positions at Alligator Creek on the east side of the Lunga perimeter. Ichiki's assault was defeated with heavy losses. The Marines counterattacked Ichiki's surviving troops after daybreak, killing many more. All but 128 of the original 917 of the Ichiki Regiment's First Element died.

Question: how many personnel were in the allied force?
11,000