Shape-Shifters is based on the short story "On The Use Of Shape-Shifters In Warfare" by Marko Kloos
One of the marines is called John Sobieski. John III Sobieski (Polish: Jan III Sobieski) was a Polish king that led the largest cavalry charge in history to save Vienna from a Turkish attack.
Sobieski is from Texas as shown by the flag hanging above his cot