An interesting take on battle and aliens. A group of US WW2 soldiers grabbed by aliens just before they die and moved to another world to be used for experiments in warfare.
They develop variations on existing weapons and test them in life & death situations, successfully.
Eventually they come against some SS troops that another alien group (read invaders) have grabbed to try & eliminate the US troops. However, there is no real explanation of what the SS group were told so that they would go after the US troops. Eventually they join forces & go ahead.
The finish is left as a cliff-hanger when they are moved to another planet to continue fighting. Normally, cliff-hangers aren't too bad if the follow on is released reasonably soon after, however, 4 years can be a very long time.
Please, launch the sequel. Apart from this, I was fully engrossed in the story as it developed & felt that the concept was entirely plausible. Well done.