WI. Allies launch a "Halifax Explosion" type attack in WW2.

https://en.wikipedia.org/wiki/Halifax_Explosion

Here is a link to a wikipedia article on the Great Halifax Explosion. In summary an ammunition ship blew up in Halifax harbour in 1917 with a force roughly equivalent to a 3 Kiloton blast. It was a disaster for the city of Halifax.

Could it have been possible to use a common ordinary merchant steamer as a weapon against an enemy anchorage or harbour? Packed with 7 or 8 thousands tons of Torpex I would guesstimate the explosive force would be nearly 10 Kilotons. If the ship could be sailed into close vicinity of the targets it would likely destroy them.

But the ship would need to be disguised as belonging to which ever Axis nation that is being attacked merchant fleet. So the ship would need be some old cargo steamer of the common type operated by everybody post WW1 up to WW2. Of course it would be flying the enemy's flag as it approached the harbour or anchorage.

How to get the ship near to its target? It would need to be sailed along a very carefully planned route taking advantage of night time and bad weather to avoid as much as possible naval and air patrols. The ship would also be escorted by a submarine.

The submarine is a necessary part of the plan for 3 reasons. To protect the ship enroute if it is stopped by an enemy patrol vessel. To remove the ships' crew just before the final run in to target. And to provide helm steering guidance via a remote control via a radio link. The sub, at periscope depth follows the ship at a safe distance (about 2 miles or so) observing the ship and with its antenna extending above the surface transmits signals to steer the ship into its targets.

I think the cargo ships' engines could be rigged to operate without attention for a few hours. And steering the ship remotely solves the ethical problem of finding someone to conn the ship on its last voyage. Would the Allies consider asking or using a few volunteers for a certain death mission? I don't think so.

Would would be the reaction of the coastal battery or naval patrol to the approach of an unarmed and harmless looking medium sized freighter puttering in at about 5 or 6 knots flying their flag? It's not answering hails or displaying the correct signal lights or signal flags.
Just to complete the disguise there should be some deck cargo like a few trucks or cattle in pens and other innocuous looking things.

How would the enemy react? They have no idea what it really is. Now the ship is not expected and it's not following protocol. But would they start shelling or bombing an obviously harmless looking merchant ship flying their flag because someone screwed up? Who would be in a hurry to make that decision that apparently entails destroying one of your own ships? Why hurry? "Let's just wait until it arrives at the dock and then we can sort out this silly bastard."

With a 10 Kiloton blast that ship doesn't have to be right on top of the intended targets. And it would be fitted with multiple redundant detonators using contact, timing and and radio from the submarine to ensure that there is no chance of the ship failing to explode.

Because this operation is dependant on subterfuge the Allies will only get one chance to conduct an attack like this one. So the target must be chosen carefully to take advantage of the maximum effect. It also must be a target that has merchant ships showing up frequently.

So where to detonate a 10 Kiloton bomb ship?
Hamburg, where the U-boats are being constructed?
Truk, the big fleet anchorage and base for the IJN?
What are other appropriate targets?
 
You mean like the HMS Campbeltown attack during the raid on St Nazaire? She was a combination ram ship and explosive carrying vessel.

No, sorry but I definitely do not mean the same as the Saint Nazaire Raid. That was clearly an attack and was fought as one. My intent is to sneak into a harbour and detonate a 10 Kiloton bomb. We are after much bigger prey than a drydock. An entire fleet maybe.
 

nbcman

Donor
No, sorry but I definitely do not mean the same as the Saint Nazaire Raid. That was clearly an attack and was fought as one. My intent is to sneak into a harbour and detonate a 10 Kiloton bomb. We are after much bigger prey than a drydock. An entire fleet maybe.
Germany didn't have much of a 'fleet' to begin with. And subs were typically kept in protected pens which would make it difficult to take out all subs in a single port.

It would be unlikely that an unexpected merchant ship could cross many hundreds of kms in the Pacific to attack a Japanese anchorage.
 
Germany didn't have much of a 'fleet' to begin with. And subs were typically kept in protected pens which would make it difficult to take out all subs in a single port.
It would be unlikely that an unexpected merchant ship could cross many hundreds of kms in the Pacific to attack a Japanese anchorage.

That's true. It is a little bit far fetched. But if you only have one chance to give the enemy a 10 Kiloton surprise where do you send it to?
 
This really seems more like an opportunity for the Axis than the Allies. They have way more good targets, and the Allies have way more merchant ships from all sorts of countries to disguise your bombship as.
 

nbcman

Donor
That's true. It is a little bit far fetched. But if you only have one chance to give the enemy a 10 Kiloton surprise where do you send it to?
Maybe a port that could disrupt the German economy like Narvik which could block iron ore imports from Sweden during the winter. But I don’t think that a single explosion would be able to do enough damage to completely stop a port from operations for an extended time. Blowing up a dry dock is another option but the large Japanese drydocks are far out of reach and Germany never built that many large ships after 1940.
 
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I don't think the British would approve such an operation. Maybe Japan or Germany trying their luck at Suez or Panama but both are heavily regulated and guarded. I feel like any unexpected vessel would likely be stopped if it was approaching a naval base in wartime. I feel like you would have a better chance with a captured vessel but even then...
 
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Well the way the Campelltown was used is i think the best way to use these things, destroy drydocks and such to prevent large warships from being build or repaired.

But, how about an assault on the Keroman submarine base, specifically the pens? Not sure how much damage such an explosion can do to a bunker-like base like that though. Those pens are specifically designed to withstand explosions. If only you can get a ship inside. They might be able to block the port though.
 
Maybe a port that could disrupt the German economy like Narvik which could block iron ore imports from Sweden during the winter. But I don’t think that a single explosion would be able to do enough damage to completely stop a port from operations for an extended time. Blowing up a dry dock is another option but the large Japanese drydocks are far out of reach and Germany never built that many large ships after 1940.

Tripoli would be the most productive target. The only practical supply port for the Axis armies in Africa. The trick is to get a bomb ship into the harbor.

Have been pondering a submarine reworked for the task. A skeleton crew, stripped for maximum pay load, if a attached mini sub can evacuate the skeleton crew... Approach and entry would require extensive reconnaissance, and a very slow/silent run in. Not sure if all that can be brought together, but combined with a maximum effort with air bombings, & regular naval interdiction it could cut the Tripoli port intake to below critical levels long enough to cripple the Axis armies in Lybia.
 
This really seems more like an opportunity for the Axis than the Allies. They have way more good targets, and the Allies have way more merchant ships from all sorts of countries to disguise your bombship as.

Yeah, it's a good thing the Axis never tried that. Considering all the wild ideas the Germans pursued.
And it's possible that the Allies, especially the Canadians and Americans far from the fronts, would be less likely to fire on an Allied or neutral flagged merchant ship acting erratically but appearing harmless.
 
I don't think the British would approve such an operation. Maybe Japan or Germany trying their luck at Suez or Panama but both are heavily regulated and guarded. I feel like any unexpected vessel would likely be stopped if it was approaching a naval base in wartime. I feel like you would have a better chance with a captured vessel but even then...

Have you heard of an old movie called Captain Scarface?
 
But, how about an assault on the Keroman submarine base, specifically the pens? Not sure how much damage such an explosion can do to a bunker-like base like that though. Those pens are specifically designed to withstand explosions. If only you can get a ship inside. They might be able to block the port though.

That could be the best possible use for the bomb ship if it could get close enough. Could the U-Boat pens survive a 10 Kiloton blast at sea level from directly in front of their portals from a couple of hundred feet away? I don't think they could. The pens were designed mainly to withstand bombing from aircraft and they were massive. But a tactical nuke sized blast pushing a water shock wave into their portals would blow the roof off I think. And mangle everything inside.
 
That could be the best possible use for the bomb ship if it could get close enough. Could the U-Boat pens survive a 10 Kiloton blast at sea level from directly in front of their portals from a couple of hundred feet away? I don't think they could. The pens were designed mainly to withstand bombing from aircraft and they were massive. But a tactical nuke sized blast pushing a water shock wave into their portals would blow the roof off I think. And mangle everything inside.

Even if the pen structure was intact the death & maiming of skilled technicians, loss of communications, electric power, ect would disrupt operations for weeks even months. Maybe add containers of phosphorus bombs on top of the ship, so they scatter across the port area?
 
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