I have had an opportunity to poke around some more in the site where I previously found WW2 era bottles. My NA Beverage passes directly over this area, and I never would have found it otherwise.
After spending some time at the location, I’ve located some shallow depressions from what probably were foxholes. I was not able to find any more bottles with marks, however several matched the Japanese style of manufacturing (very thick glass, not precision made).
With a metal detector, I located a large number of live .30 rifle rounds. All were stamped “43″ (1943) which were used with the M1 Carbine, a rifle used extensively during the liberation of Guam. Even more interesting was a fully loaded carbine magazine I found.
I also dug up a number of artillery fuses, likely still live. The purpose of this site is clear. Due to the thick overgrowth and limited number of people living on the northern end of the island, it became almost impossible to maintain a solid front line as the Americans pushed northward. Units quickly became separated in the jungle. Since Japanese resistance was focused along the few roads, this is where the GIs focused their efforts. This was either the stopping point along the front lines during the liberation, or a post-liberation base camps where patrols would be sent out to search for Japanese stragglers hiding in the jungle.