USS Massachusets V Jean Bart

[paul.mercer]

Gentlemen,
In another thread (Hits below the waterline) a post included USS Massachusetts is engaging and firing upon the French battleship Jean Bart, what were the circumstances of the action?

[Steve Crandell]

Gentlemen,
In another thread (Hits below the waterline) a post included USS Massachusetts is engaging and firing upon the French battleship Jean Bart, what were the circumstances of the action?

On 8 Nov 1942 USS Massachusettes shelled Jean Bart, which was tied up at the pier in the Vichy French Port of Casablanca. Jean Bart fired back. This was part of the Allied invasion of Vichy French North Africa.

You can google this pretty easily and get detailed information.

[Mostlyharmless]

....snip....
You can google this pretty easily and get detailed information.

Good luck finding out the range at which the various hits were scored. You might find yourself led into a fascinating debate over how a 2,700 lb. shell penetrated the 150 mm main armour deck after passing through a 25 mm (?) weather deck and before passing through a 40 mm lower deck.

[Byron Angel]

"French Battleships 1922-1956" by Jordan & Dumas offers detailed coverage of Jean Bart's damage, with info sourced from the original French post-battle damage report. My theory (subject to confirmation when/if I ever get the time) is that Jean Bart may not have been perfectly upright at her berth as a result of relatively minor but uncorrected flooding from damage by prior aerial attack.

B

[Mostlyharmless]

I haven't read Jordan & Dumas. Do they describe how the sections of Jean Bart's main deck were fixed together? For example, South Dakota or Iowa's main deck consists of 4.75 inch plates laid on top of 1.25 inch plates (with a 5/8th inch plate below), King George V has either 200 lb plate or 160 lb plate on top of a 40 lb plate whilst I think that Littorio has 150 mm or 100 mm armour on top of 12 mm construction steel. However, Bismarck had simply a single 80 mm and 95 mm deck welded together.

[Byron Angel]

I haven't read Jordan & Dumas. Do they describe how the sections of Jean Bart's main deck were fixed together? For example, South Dakota or Iowa's main deck consists of 4.75 inch plates laid on top of 1.25 inch plates (with a 5/8th inch plate below), King George V has either 200 lb plate or 160 lb plate on top of a 40 lb plate whilst I think that Littorio has 150 mm or 100 mm armour on top of 12 mm construction steel. However, Bismarck had simply a single 80 mm and 95 mm deck welded together.

..... According to Jordan and Dumas:

quote -

"The upper armoured deck (PBS), which was a main deck level, comprised thick non-cemented armour plates without a backing. The plates were laid lengthways and were 150mm thick over the machinery (frames 51.50 to 130.00), increasing to 170mm over the forward magazines (frames 130.00 to 182.95).

The lower armoured deck (PBI), which was on the level of the first platform deck, was of similar composition but at a much-reduced thickness: 40mm on the broader horizontal section and 50mm on the inclined sides which joined the lower armoured deck to the lower edge of the armour belt."

- unquote

The detail diagrams show all deck armor plates laid directly upon the girders without any backing plates. The upper armored deck was positioned at the top of the armour belt; the horizontal component of the lower armored deck was positioned at about mid-height of the armor belt with its transverse extremities sharply turned down to meet its lower edge.

A quick re-read of the authors' account of the action appears to lend support to the theory that JEAN BART may not have been upon a fully even keel at the time she was taken under fire by MASSACHUSETTS -

0718 - JEAN BART damaged by two 500lb bomb hits in an initial air attack: one bomb struck the port catapult mount which caused "a small fire and flooding of the manual steering compartment"; a second bomb "struck the quay to starboard, causing a large breech in the outer hull plating in section M".

0725 - First hit by MASSACHUSETTS on shelter deck aft, seven minutes later, passed through both armored decks and exploded in the empty 152mm magazine compartment. French examination of the path of the hit (which passed through four decks) estimated striking angle relative to the ship's decks as 33 degrees. The line of fire of MASSACHUSETTS for this hit, judging from the damage diagrams given in the book, was approximately 30deg off the starboard bow of JEAN BART. Any flooding suffered by JEAN BART as a result of the aerial bomb hit on the quay would have produced a list to starboard, which would have effectively increased the angle of presentation of her decks to an projectile approaching from that side.

FWIW

B

[Dave Saxton]

Additionally, Toebicke testified that the quality of French armour plate was abysmal.

[aurora]

While the Jean Bart was only partially completed, unable to get underway and had a marginally trained crew, the battle between her and the USS Massachusetts has some value in examining the damage Jean Bart received. Between 0704 and 0810 on November 8th the Massachusetts fired over 200 rounds at either the Jean Bart or the costal defense battery, El Hank. Of these shells a total of five struck Jean Bart. These hits caused the following damage:

At 0725 the first hit was registered. This shell struck the starboard side aft penetrating the 6" armored deck, the 11/2" splinter armor below, and then entered an empty 152mm magazine were it detonated. Had this magazine been fully loaded it, along with the two beside it, would have likely blown the stern off the Jean Bart.

At 0737 a second shell hit Jean Bart to starboard just aft of the funnel which exited the ship just above the waterline forward of the port 152mm barbette. At sea this shell would likely have resulted in local flooding above the armored deck.

The next hit was made at 0806 striking Turret I at an oblique angle glancing off the 6" barbette armor. This armor was badly gouged by this strike resulting in a jamming of the turret in train. In action at sea this would have taken the turret out of action. As it was this turret was unable to operate for over ten hours while a local contractor cut away the damaged area.

A second shell from this salvo struck Turret II's barbette (this turret was not complete and non-operational) also at a very oblique angle continuing aft into the ship's hull. There it wrecked a number of spaces coming to rest next to the communications tube connecting the conning tower.

The last shell struck starboard aft just ahead of the starboard catapult mounting. This shell penetrated the 4" armor protecting the steering gear and detonated just above the keel. Jean Bart 's steering gear was largely wrecked by this hit.

Massachusetts was not hit during this action although Jean Bart did manage to fire a good number or 2 or 4 gun salvos including getting straddles on the cruiser Augusta.