Legion of Liberty (book)

In the Americas, a tiny percentage of people develop superpowers around the age of 12. All of the European powers are competing for colonization in part to acquire these superhumans and use them in their ongoing power struggles in Europe. The British conscript their superhumans into the Royal Superhuman Regiment - the notorious Greycoats; the Sons of Liberty, however, have hidden some young superhumans, waiting for the right time to rebel against the tyranny of King George.