Charles Emory Smith,
Appletons' Cyclopædia of American Biography
(1900)
“ Blaine, who, with other American statesmen, resisted the English doctrine of perpetual allegiance, and maintained that a naturalized American was entitled to the same protection abroad that would be given to a native American, took active part in pressing these questions upon public attention, and, as the result of the agitation, Costello was released. The discussion of these cases led to the treaty of 1870, in which Great Britain abandoned the doctrine of “once a subject always a subject,” and accepted the American principle of equal rights and protection for adopted and for native citizens. ”
