From my listenings, i've interpreted that this song is about the Imperial Japanese army's occupation of the Pacific rim islands during WW2. Here is my casual line-by-line analysis:
"On a thousand islands in the sea" A reference to the cavalcade of different islands that Japan occupied in the Pacific during the early stages of WW2.
"I see a thousand people just like me"
The uniformity of the military, especially the imperial Japanese's, is reflected. Alternatively, it could be a questionable reference to the dodgy opinion that all Japanese resemble each other 
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"A hundred unions in the snow" A flurry of soldiers hurrying to hastily be wed before being shipped away to their theatres of duty.
"I watch them walking, falling in a row" The dichotomy of the wedding march and the military march. Falling into bed(or tatami) for final consumation, and falling into the dirt in final sacrifice to empire and emperor. Also, perhaps the observation of a Japanese guard at the Bataan Death March.
"We live always underground" After the initial interval of confusion post-Pearl Harbor in which Japan had the mobility advantage, the U.S. forces began to Island Hop on their way to Japan. Unable to prepare enough concrete defenses against naval bombardment during beachheads, Japanese garrison troops dug deep earthenwork spider holes and entrenched caverns to defend themselves.
"It's going to be so quiet in here tonight" Reference to either being alone on guard duty as one's unit is on patrol or dwindling to death from starvation or attack.
"A thousand islands in the seait's a shame" According to the tenets of Yamato Damashi, no Imperial Japanese solider was to be captured or to surrender to the enemy. This philosophy resulted in massive bodycounts and slaughter as neither Japanese army or U.S. Marines were trained to surrender to an enemy force unless ordered to.
"And a hundred years agoA sailor trod this ground I stood upon" European traders and explorers searching for new outposts and trade routes via the Pacific Rim in the mid 1800s.
"Take me away, everyoneWhen it hurts thou" Either a request to be helped when wounded in battle or for one to be selflessly killed off in assisted suicide rather than impede the progress of their comrades.
"From my head to my toesFrom the words in the bookI see a vision that would bring me luck" "The "moral national Bible" The Subject's Way presented an effective catechism on nation, religion, cultural, social and ideological topics. All citizens needed to have it."
"From my head to my toesTo my teeth, through my nose" The interpretations from here on get a bit more subjective, but on Iwo Jima, the volcanic dust and sand permeated all equipment and orphices.
"You get these words wrongYou get these words wrongEverytimeYou get these words wrongI just smile" Perhaps captured Allied troops or natives attempting to speak to their captors in pidgin Japanese.
"But from my head to my toesFrom my knees to my eyesEverytime I watch the skyFor these last few days leave me aloneBut for these last few days leave me aloneLeave me aloneLeave me alone" A futile plea for aerial and naval bombardment to give the ragged defenders a few moments of respite in their last days of resistance before the inevitable collapse of not just themselves, but Imperial Japan itself.
So am I right or am I right? 
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. I admit yes, the "unions in the snow" interpretation was a little farfetched, I had a specific scene from my favorite warflick in mind at the time(which, incidentally, co-stars Frank Sinatra).
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