Thread by @navalhistorian

On this day 1941, the @RoyalNavy's Force H under V/Adm Sir James Somerville, aboard the battlecruiser HMS Renown, with the battleship HMS Malaya, aircraft carrier HMS Ark Royal & cruiser HMS Sheffield, arrived off the Italian port of Genoa & opened fire #WW2

Just a week before, Force H had attempted to breach the enormous Santa Chiara dam on Sardinia’s Tirso River (two years before the famous attack by @RoyalAirForce's @OC617Sqn), using torpedoes dropped by @RoyalNavy Fairey Swordfish from 810 NAS aboard HMS Ark Royal.

Led by Lt/Cdr Mervyn ‘Johnnie’ Johnstone, this spectacular attack on one of Europe's biggest dams was unsuccessful, thwarted by a combination of foul weather, Italian AA fire & what was believed to be an unexpected sandbank that grounded the torpedoes before they hit the dam wall

The foul weather that day had also caused V/Adm Somerville to call off the bombardment of Genoa he had planned as a followup to the dam, but, determined to carry it out, Force H had returned. This time, finding the weather was much improved, they approached to within firing range

The targets were numerous. 14 Swordfish from 810 & @820NAS took off from HMS Ark Royal to bomb the big oil refinery at Livorno. Another four went to mine the entrance to the Italian Fleet’s new main base at La Spezia to try to prevent them interfering with Force H’s withdrawal.

Meanwhile, at Genoa itself, perhaps Italy's biggest port, were the fixtures, fittings and great warehouses of the dockyard, the Ansaldo armaments works & the railway marshalling yards that fed the port and its industries.

Perhaps the key target however, was the modernised battleship Caio Duilio, in dry dock undergoing repairs to damage suffered at Taranto.

V/Adm Somerville described the scene in a letter home to his wife (via @NavyRecords):
"About 6.45 a dull smudge ahead of us showed the high mountains behind Genoa... Not a sign from shore, not a ship except our own on the sea. We steamed up to the beginning of the run, i.e. about

10 miles off Genoa and then flash went the broadsides. Of Genoa itself we could see nothing. Our guns were laid by gyro and our aircraft over the town spotted us on to the various targets. The first salvoes fell almost exactly where we wanted them and then I felt content...

The curtain was up and the tragedy was on. For half an hour we blazed away and I had to think of Senglea, Valetta, London and Bristol, etc., to hardenmy heart. But I was watching the map and the reports of the aircraft and I do believe that practically all of our salvoes fell on

works, warehouses, shipping, docks, etc. Still, it's no use pretending that some innocent people were [not?] killed. War is lousy."

Thirty minutes later, V/Adm Somerville turned Force H away & headded full speed for Gibraltar & home. The Italian fleet, which was already at sea (& therefore not hindered by the mines dropped by HMS Ark Royal's Swordfish) came close, but was unable to engage, while Italian air..

strikes scored no hits, & Force H returned, undamaged to Gibraltar.
The damage at in Italy was extensive, but relatively superficial. Though starting some fires, HMS Ark Royal's Swordfish lacked both the numbers & bombs todo serious damage to a large oil refinery, while the...

port, industrial & transport infrastructure targeted at Genoa demonstrated its well known resilience, even in the face of the 1,938lb shells fired by the great 15in guns of HMS Renown & HMS Malaya & of the 40 or so merchant ships hit, only 5 were actually sunk.

Crucially, much like the Tirso Dam a week before, Caio Duilio had survived; missed entirely under smoke from fires.
Despite their audacity, with both of these targets still intact, ops Picket & Grog were therefore relatively moderate sucesses compared to ops Judgement & Chastise

Do check out this brief @HistoryToday article from 2016, looking at Britain's first attempt to breach a dam in #WW2, the subsequent bombardment of Genoa, & a notable reminder of the event held in Genoa Cathedral historytoday.com/first-dambuste…