[dragoon500ly]

American radio intelligence monitored the dispatch sending Ichiki into the area. While they were unable to determine the contents of the message, they were able to confirm the movement of IJA reinforcements. By August 17th, Intelligence was able to place a special shock unit in the Guadalcanal area. Their belief was that an attack on the airfield would accure sometime around August 20th.

On August 12th, a few engineers began a movement to thte Tetere area to survey a possible airfield site, leading to the Marines first contact with Ichiki. A rifle platoon was detached as escort and was informed on the 13th of rumors that a Japanese force had landed further east. The platoon leader decided to return to the Marine perimeter to report the intelligence and to take a larger force out to verify it.

On August 19th, a combat patrol of 60 men from Company A, 1st Bn, 1st Marines entered the jungle. At the same time, Ichiki sent a patrol of 38 men ahead to set up a radio station near Alligator Creek.

About noon, as the Marines halted for rest and food, native guides warned them of the approach of the Japanese. The Marines prepared a hasty ambush. In a firefight that lasted roughly an hour, the marines killed all but 5 of the Japanese, the survivors escaping back into the brush. The marines lost 3 killed and 3 wounded. Examining the ambush site, the marines noted that the dead Japanese wore the star of the Imperial Army instead of the chrysanthemum of the Imperial Navy. The new condition of their uniforms confirmed their recent arrival on the island and the large amount of communications equipment betrayed the presence of a larger unit. A map was also captured that revealed in stunning detail that the Japanese knew that the Marine defenses on Alligator Creek extended only a short distance inland.

Word reached Ichiki about 1630 of the clash between his commo party and an American company. He rushed forward with one company to help and confirmed the destruction of his party. Ichiki pressed on and did not halt until 0430 hours after he crossed the Nalimbu River.

The captured Japanese map and other documents told General Vandegrift that the unit was regimental sized and had recently left Guam. They did not tell him of the exact size, location and intentions of this force. The map not only illustrated the Marine positions along Alligator Creek, but also accurately depicted the Marine artillery positions near the airstrip.

Faced with a series of difficult choice, Vandegrift had to make a decision. His staff recommend that he unleash his only reserve battalion to attack the approaching the Japanese. But lacking clear information as to the enemy strength and intentions, and being left without a reserve, he made the decision to await the Japanese attack within his perimeter.