Having earned a mention in dispatches for his "Zeal and intrepidity" in the boat action with "Potomac", Birchall was made a commander in 1797 and by 1798, had commissioned the lightly armed but fast troopship, "Hebe". In May, she was serving in a squadron under Home Popham, sent to prevent the movement of a large number of enemy barges from Vlissingen to Dunkirk. The large flat-bottomed boats were to be used to convey troops across the Channel for Napoleon's planned invasion of the United Kingdom. At that time, the flotilla was travelling along the inland waterways of Belgium to Ostend, where the British hoped to stop them by destroying the lock gates and sluices there. A force was gathered at Margate, comprising 25 small vessels, of which Popham's 26-gun "Expedition" was the largest, and over 1,000 troops, a good proportion of which were held aboard "Hebe".