They attacked and quickly defeated the Insular Force Guard in Agana .
The Japanese landed about 400 troops of the 5th Defence Force from Saipan on Guam in the early morning of 10 December 1941 , at Dungcas Beach , north of Agana .
Japanese attacked and quickly defeated the Insular Force Guard in Agana .
The Japanese landed about 400 troops of the 5th Defence Force from Saipan on Guam in the early morning of 10 December 1941 , at Dungcas Beach , north of Agana .