as completely as Napoleon's, once the British Navy had
begun its concerted movements on a comprehensive scale.
From that time forward the British began to win the naval
war, although they won no battles and only one duel that
has lived in history. This dramatic duel, fought between
the _Shannon_ and the _Chesapeake_ on June 1, 1813, was
not itself a more decisive victory for the British than
previous frigate duels had been for the Americans. But
it serves better than any other special event to mark
the change from the first period, when the Americans
roved the sea as conquerors, to the second, when they
were gradually blockaded into utter impotence.

Having now followed the thread of naval events to a point
beyond the other limits of this chapter, we must return to
the American movements against the Canadian frontier and
the British counter-movements intended to checkmate them.

Quebec and Halifax, the two great Canadian seaports, were
safe from immediate American attack; though Quebec was
the ultimate objective of the Americans all through the
war. But the frontier west of Quebec offered several
tempting chances for a vigorous invasion, if the American
naval and military forces could only be made to work
together. The whole life of Canada there depended absolutely
on her inland waterways. If the Americans could cut the
line of the St Lawrence and Great Lakes at any critical
point, the British would lose everything to the west of
it; and there were several critical points of connection
along this line. St Joseph's Island, commanding the