One of the first operations that Force H took part in was connected with the reason for its formation. French naval power still existed in the Mediterranean, and the British Government viewed it as a threat to British interests. It was feared that the Vichy government of Philippe Pétain would hand the ships over to Germany, despite a vow that that would never happen. Such an incidence would almost certainly decisively tip the balance against Britain in the Mediterranean. Consequently, Force H was ordered to execute Operation Catapult.
The most powerful of the remaining French forces was in port at Mers-el-Kébir in Algeria. It consisted of the French battleships Strasbourg and Dunkerque, two older battleships, along with escorting vessels. Force H steamed to off the Algerian coast, and an envoy was sent to the French commander. Various terms were offered, including internment of the fleet in a neutral country, joining the British forces, or scuttling the fleet at its berths. However, the commander of the French forces reported only the scuttling option to his superiors. He was thus ordered to fight. The reasons for the omission have been debated by many. It is often thought that the anti-British bias of the French commander was to blame.
The result of the action was that the remains of the French fleet escaped to Toulon, a French base on the Mediterranean coast of metropolitan France. They did so at heavy cost. The French battleship Bretagne blew up under British gunfire, killing over 1,000 French sailors. The battleship Provence was also badly damaged; Strasbourg and Dunkerque were also hit, although Strasbourg escaped with four destroyers.
After this unpleasant operation, Force H settled down to its more normal operations. These involved general naval tasks in the western basin of the Mediterranean. Prominent amongst these tasks was fighting convoys through to Malta. The early convoys came through with relatively light losses. That changed in 1941, when the Germans sent the Luftwaffe's X. Fliegerkorps to Sicily; its bombers took a high toll of both warships and merchantmen. Also, from 1942 the improved combat efficiency of the Regia Aeronautica (and especially of its SM.79 torpedo bombers) and of the Regia Marina's submarines posed a far greater threat to these convoys than the 1940 Italian opposition.