In July and September 1941 Iachino led the fleet in fruitless attempts to intercept British convoys to Malta (Operation Substance and Operation Halberd). During the First Battle of Sirte (16 December 1941) and the Second Battle of Sirte (22 March 1942) the forces under his command clashed with the escorts of British convoys heading for Malta, but despite his superior strength Iachino – concerned about not underestimating the enemy forces (to the point of believing incorrect reports about nonexistent battleships) and avoiding night action, both of which had been his fatal mistakes at Matapan – did not press the attack and was unable to cause significant damage to the convoys.