Meantime, however, the British Government had determined, as said, on an invasion like that of the defeated Burgoyne, in the Revolutionary war--an invasion that should cut the nation in two on the line of the Hudson. To accomplish this it was necessary to gain complete control of Lake Champlain. The country had been so far improved that an army could find a roadway along the lake and away to the south, where Burgoyne had been obliged to hew his way through a wilderness; but the control of the lake was, nevertheless, essential. To hold the control they supposed they had when they captured the sloops _Growler_ and _Eagle_, they had built the brig _Linnet_, a vessel of the exact size of the American schooner _Ticonderoga_. But when they found that Macdonough had brought out a corvette (she measured about seven hundred and thirty-four tons) they laid down the keel of a frigate, the exact size of which is nowhere given, but it rated, later, in our navy with the frigates of 1,400 tons. The lowest estimate of her size places it at 1,200 tons. She was built at Isle-aux-Noix in the Sorel--the outlet of Lake Champlain--and was launched on August 25, 1814. Hearing of the work upon her, Macdonough returned to Vergennes, on the Otter Creek, and once more made the air resound with the slash and rasp and click of broadaxe, saw, and maul. The keel of a brig was laid on July 29th, and on August 16th she slid into the water--she had been built in nineteen days! And yet she was about as large as the _Lawrence_ and the _Niagara_, with which Perry won the victory of Lake Erie--she measured well up toward five hundred tons. She was called the _Surprise_, at first, but the name was changed to _Eagle_ later on. [Illustration: Thomas Macdonough. _From an engraving by Forrest of the portrait by Jarvis._]