At 1754 on 3 July 1940, at the maximum visibility distance of 17,500 yards, HMS Hood, followed by HMS Valiant and Resolution, opened fire on the French warships in the harbour of Mers-el-Kébir. During the next 10 minutes, the three capital ships fired 12 salvoes apiece, amounting to 144 15in (380mm) rounds. Force `H’, besides the three capital ships, consisted of the light cruisers Arethusa and Enterprise, which were tasked with replying to shore batteries, and the destroyers Faulknor, Foxhound, Forester, Keppel, Active and Vidette, screening against submarine or destroyer attack.
The first salvo fell short but the next hit the breakwater, showering the French battleships with fragments of concrete. The third scored a direct hit at 1757 on the old, but modernised battleship Bretagne, causing a major explosion amidships; its commanding officer initially attempted to beach the ship but quickly appreciated that the situation was beyond hope and ordered it to be abandoned. A minute before this first hit, the Bretagne’s sister-ship, the Provence, had begun to return the British fire, simultaneously cutting the wires which secured it to the breakwater and slipping the cable forward.
The first French capital ship to get under way was the Strasbourg, whose commanding officer did not bother to cut his stern wires until after he had pulled out the bollards to which they were secured. As the ship came clear of its berth, at 1759, a salvo of shells landed where it had been lying a minute previously; thereafter, the Strasbourg was repeatedly straddled as it made its way down the harbour, but it was not hit.
As the Provence began to move clear, at 1800, Vice-amiral Gensoul’s flagship, the battlecruiser Dunkerque, opened fire on Force `H’. Just as it finished casting off, however, it was hit first by a 15in shell which passed through the aircraft hangar aft without causing serious damage and then, as the commanding officer `rang down’ for 12 knots, by three more heavy shells from a single salvo. Of these, one ricocheted off the upper 13in (330mm) turret, another penetrated the side armour and exploded inboard, causing severe damage and fires, the smoke from which caused the abandonment of the starboard engine-room; the third shell hit on the waterline amidships, penetrating the armoured belt, two anti-torpedo bulkheads and the lower armoured deck, and causing fires, oil fuel flooding and severe damage to the electrical distribution system in its wake. Despite the damage, the Dunkerque continued to fire six of her eight guns until all electrical power failed, at 1808, and 5 minutes later it was anchored in the harbour.
The ships’ return fire was at first very short, but accuracy improved and although no hits were obtained, the British ships were near-missed and in some instances bracketed by French salvoes, the Hood sustaining minor damage from splinters which wounded two men. The bombarding squadron maintained an easterly heading until 1801, when the increasingly accurate fire of the shore batteries resulted in the British ships turning away to reverse track to the westwards, Somerville ordering them to make smoke to obscure the view from the forts.
By 1801, the Provence had steamed about 500 yards from its berth when it, too, was hit by a 15in shell. This caused a very serious fire aft and the after portion of the ship was flooded as the result of a section of armour plate being detached by shock. Like the Dunkerque, it came to anchor in the harbour. The Bretagne, badly on fire, took more hits and capsized at 1807 with the loss of 907 officers and men.
Six contre-torpilleurs, large destroyers armed with cruiser-calibre guns, were either under way or preparing to un-moor when the first salvo was fired by Force `H’. The closest to the harbour entrance was the Mogador and it was hit at the same time as the Bretagne (1757); struck aft by a 15in shell which detonated 16 depth-charges, it lost its stern, its hull was wrecked as far forward as the machinery spaces and, reduced to a hulk, was abandoned at 1802 by all but its fire-fighting parties. Only two of the other large destroyers sustained any damage while escaping from the harbour, the Volta being showered with concrete fragments from a hit on the breakwater and the Lynx being holed by splinters from a near-miss shell; neither sustained any personnel casualties.
Two tugs were also hit by splinters, but the seaplane-carrier Commandant Teste, one of the largest targets, was untouched, even though it remained at its mooring at the end of the line of capital ships throughout the bombardment. The shooting had been very accurate, for only six heavy shells had been strays, five landing in the hinterland and another decapitating the Mers-el-Kébir lighthouse.
Force `H’ ceased fire at 1804, as soon as it had become apparent that the French ships were no longer replying. The gunnery of the coast-defence batteries had become increasingly accurate and this forced Vice-Admiral Somerville to turn away and head westwards under a smoke-screen. Already far to the north-west of the entrance to Mers-el-Kébir, this turn took him away from the Strasbourg, which passed through the gap in the outer boom at 1807, clear of the five mines laid by the Ark Royal’s aircraft. She made good her escape to the east, in company with the five contre-torpilleurs.
At 1813, Amiral Gensoul ordered a large square sail to be raised by the Dunkerque and passed a message to the wireless station to be forwarded to Force `H’: `Vous demande de cesser le feu.’ This was also passed by light and wireless by several ships and shore stations but Somerville, who had already ceased fire, did not reply until 1835, when he signalled: `Unless I see your ships sinking, I shall open fire again.’ It was, indeed, impossible to see anything in Mers-el-Kébir harbour from Force `H’ and even the spotter aircraft were having difficulty because of the palls of smoke from the burning ships and the late-afternoon haze. But, by this time, Somerville had a further problem, which was to spare Mers-el-Kébir a further bombardment.
As early as 1804, an aircraft reported that the Strasbourg was under way in the harbour. At 1813, three destroyers were seen to be heading east and 5 minutes later the aircraft reported that a battle cruiser was also clear and making to the east. Somerville was disinclined to believe this last report:
In view of other reports of movements which had subsequently been cancelled, the difficulty of observation due to smoke and the certainty I entertained that the French would abandon their ships, I did not attach sufficient weight to this report.
Tactically, he had been completely `wrong-footed’, primarily because, contrary to his own orders, he was in completely the wrong position to cut off any attempted break-out. The cause of his disbelief in airborne observation, he explained, was the earlier sequence of reports of confused boat traffic and the movement of submarines (the purpose of which had been quickly and accurately surmised by the airborne observers), but once the action had started there was little justification for doubting the aircraft reports. The worst possible outcome of Operation `Catapult’ was an escape by French capital ships, but Somerville still believed what he had been told a week previously about French naval morale and he had not made adequate provision on the day.
Twelve minutes elapsed, while Force `H’ steered north-west at 18 knots and the Strasbourg headed north-east at 28 knots, before another aircraft report convinced him, at 1830, that a major break-out had occurred; by the time that he actually turned Force `H’ to the east, eight minutes later, the French ships were some 25 miles ahead.
The Ark Royal had meanwhile received somewhat of a fright. She had been operating independently of the capital ships throughout the day and, screened by three destroyers, she was some 18 miles to the north of Oran when an aircraft report was received at 1835 that the Strasbourg was within easy gun range of the carrier, should the visibility improve. Immediately after the receipt of the report, the bowwaves of two of the French destroyers were sighted from the Ark Royal’s bridge. The carrier was immediately turned away and headed north-west at 30 knots, to avoid contact and to seek support from Force `H’. Not only had Somerville failed to prevent the escape of the Strasbourg – he had come perilously close to losing his own carrier!
The Ark Royal had just completed launching six Swordfish and three Skua fighters as escorts when this near contact occurred. These aircraft were a belated contribution to the `Anvil’ phase and were armed with 250lb and 20lb bombs `to destroy morale, damage A/A equipment and induce French crews to abandon ships’. Vice-Admiral Wells subsequently reported that at 1840, `as it appeared that the enemy battle-cruiser outside the harbour might escape Eastwards, bomber striking force was ordered by W/T to attack this ship’. This was a curious statement, for by that time it was patently obvious that the Strasbourg was escaping and subsequent commentators have observed that little could have been hoped for in the way of substantial damage to a modern capital ship from such light bombs. The timing of the order suggests that the more likely reason for the order to attack was to create a diversion to permit the Ark Royal to get clear of the French ships. If, as is likely, this was indeed the case, the aircraft did not contribute to the Ark Royal’s escape, neither did they hinder the Strasbourg’s: not until an hour later did the Swordfish deliver their strike, having first staggered up to 11,000 feet to begin their dive-bombing run. All bombs missed and two aircraft were shot down, although their crews were rescued.
Admiral Somerville meanwhile was in pursuit of the Strasbourg, which had been joined by three destroyers from Oran. His two slow battleships were gradually left behind without escort as the Hood, two cruisers and all available destroyers worked up to full speed, but the Valiant was to fire the last British salvoes of the day, engaging a destroyer inshore. The Ark Royal flew off a torpedo-strike at 1950, in the hope of slowing down the Strasbourg but 30 minutes later, long before the aircraft could close the French ships, Somerville abandoned the chase: he was not gaining on the quarry, which was reported as being 25 miles ahead, and he estimated that the Strasbourg would rendezvous with the Algiers squadron’s cruisers and destroyers at about 2100.
The torpedo attack was delivered between 2055 and 2112, in the late twilight. In the poor light and thick haze, the Swordfish pilots had difficulty in estimating the speed of the Strasbourg and their range at the point of dropping. None was fired at before releasing torpedoes but, despite achieving surprise, no hits were scored.