It must have been quite an internal struggle for many of the German-Americans, whose parents might have only emigrated a couple of decades before to the USA and would no doubt still speak, act, and live 'German' at home and within their community. No doubt the heart strings were pulled when the Vaterland was mobilising, especially at that time the US had no involvement in the war, so who knows how many made the trip across the atlantic to offer their services.
SHJ