I am unfamiliar with this war poem, but the term "sucked sugar stick" is familiar. Sugar cane looks like a stick, is very sweet, is sucked to make the sugar come out, and is often give to little children as a treat. Because this is a war poem, my assumption would be that someone needed to keep a little one quiet, and therefore gave them a sugar cane stick to suck. Using a sugar cane stick is such an ordinary activity in contrast to the activities of war that it would make sucking sugar cane seem that much more visible and ordinary by contrast. Sucking the sugar cane stick could also be a symbol for the ordinary pieces of life destroyed by war.