The Peace of Amiens temporarily left Baker without a ship, but he returned to active service with the resumption of hostilities, taking command of the 36-gun on 28 April 1803. He was assigned to the Channel Fleet under Admiral William Cornwallis, and on 10 August 1805 he came across the 40-gun French frigate off Cape Finisterre. Prior to the sighting the "Phoenix" had intercepted an American merchant, en route from Bordeaux to the United States. The American master had been invited onto the "Phoenix", sold the British some of his cargo of wine, and had toured the "Phoenix" before being allowed to continue on his way. The "Phoenix" had at this time been altered to resemble from a distance a large sloop of war. The "Didon", which was carrying despatches instructing Rear-Admiral Allemand's five ships of the line to unite with the combined Franco-Spanish fleet under Vice-Admiral Pierre-Charles Villeneuve, intercepted the American merchant and from him received news that a 20-gun British frigate was at sea and might be foolish enough to attack the "Didon". The "Didon"s commander, Captain Milius, decided to await the arrival of the British ship, and take her as a prize. The "Phoenix" was therefore able to approach and engage the "Didon" before the French realised that she was a larger frigate than they had anticipated. After a sharp action lasting several hours, with Baker on one occasion having his hat shot off his head, the French surrendered. The "Phoenix" had 12 killed and 28 wounded, the French sustained losses of 27 killed and 44 wounded. By intercepting the ship carrying the despatches for Allemand, Baker had unwittingly played a role in bringing about the battle of Trafalgar, but he was to play an even greater role a few days later, possibly even staving off an invasion of England.