This essay is an outgrowth of a study of Fenianism in North America undertaken some years ago and is an attempt to compile an outline of the salient features of the problem of Canadian military responsibility as it developed after the grant of responsible government, down to the time when Britain, weary of urging Canada to take tip defensive obligations commensurate with the extent of her new political autonomy, determined to withdraw the great body of her troops and cast upon the Dominion the whole burden of its own local defence in time of peace.