2009/04/27

Offensive minelaying for European defence

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Mine laying is just like mine countermeasures (MCM) a not very 'sexy' field of naval warfare. It's not about fancy missiles, guns, fast ships - the only 'sexy' images related to naval mine warfare are about mine explosions, when a huge amount of water and gasses blows up from a calm sea. The naval mine itself isn't 'sexy' at all.


Defensive mine laying is a quite simple affair; you navigate your ship or boat to a position and drop your mines. Boring. Most importantly: This has no great requirements about the ship or boat. It can be done with modified civilian vessels.

Offensive mine laying is different, because it happens close to the enemy and thus in a high risk are. Modified civilian ships are at great risk, so purely military means of deployment are preferred.

I identified offensive mine laying as advisable part of European naval power requirements in March. It's not 100% necessary, but appeared to be a suitable approach for some challenges, especially for countering the employment of hostile submarines in European peripheral waters (Mediterranean and Baltic Sea).
Both the destructive effect as the blockade effect of offensive mine laying seem to be useful for European defence.

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Let's have a look at some historical examples for offensive mine laying:

Germany vs. British Empire (UK in particular), early WW2
Germany had developed naval mines with effective magnetic fuze (not really a novelty) by 1939 and employed it against the British. The quantity was mediocre, but the effects were disastrous. Many British ships were sunk or damaged.
The offensive mine-laying happened by destroyers, torpedo boats and aircraft - very rarely by cruisers or commerce raiders.
Some aircraft-laid naval mines were laid in poor positions and recovered by careful British experts. The investigation of the fuze confirmed the reliance of the magnetic fuze principle and the British developed several active and passive countermeasures. The magnetic-fuzed naval mines' effectiveness dropped drastically once the British had equipped enough ships, boats and even aircraft for mine-clearing.


Several mistakes can be identified in this case:

1) The fuzing principle wasn't kept secret. Some mines were laid in places (by aircraft) where the tide revealed them later - recovery was thus very much possible. The mine had furthermore no disarming traps to prevent investigation.
2) The relevant mine type relied on a single fuze principle and had initially no ship counter - a single sweep cleared a lane because the mine would explode on first contact, not after a set quantity of contacts.
3) The quantity of mines laid was insufficient - the technological surprise could have been better exploited with a sudden appearance of many more naval mines.
4) The Germans did not interfere much with the mine sweeping efforts. Air and small boats attacks against minesweepers could have hindered the British countermeasures. Armies know: Only a guarded obstacle is an obstacle.
5) Neither air power nor submarine fleet were prepared to contribute to a fatal blow against British shipping at that time. A decisive political effect couldn't be expected under such conditions.

USA vs. Japan, very late WW2
This campaign rested heavily on air-dropped naval mines and had disastrous effects on Japanese shipping because of the inability of Japan to provide the necessary mine countermeasures at that time.
They used multiple fuze principles - none of them were entirely new, but some were difficult to clear with the technology of 1945.
This campaign was executed with lavish resources and came quite sudden to the already terribly weakened Japanese forces.

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Offensive mine laying can be done very differently, for example:
- by air drop
- by air drop with a glide phase for standoff to enhance the aircraft's survivability
- surface mine laying; preferably by fast, survivable surface combatants
- covert surface mine laying; a rare technique, used by commerce raiders
- submerged mine laying by torpedo tubes; the submarine has a reduced torpedo load
- submerged mine laying by special submarine module
- submerged mine laying with self-deployment

The mines can be quite the same in these examples, albeit those laid through torpedo tubes are typically cylinders that cannot easily be camouflaged.

I emphasize a relatively low cost for the mine deployment capability and high platform survivability.

My preferences for offensive mine laying are:

1) by air drop
The U.S. Quickstrike mines - basically normal bombs with a very special fuze - are great examples for mines that can be laid by combat aircraft.


The mine laying activity could be disguised as normal approach on a ground attack mission. Only the inventory of fuzes means additional costs in this case. Preparations for offensive mine warfare done in peacetime could be relatively cheap and low-profile with such an approach. The effectiveness of the mines is probably mediocre with such a compromise design.

2) by submarine, self deploying
Old 533mm submarine torpedoes can be re-worked to self-deploying mines. They can be launched from a normal submarine many nautical miles away from the minefield position. The obsolete Mk67 SLMM is an example.
Again, this method requires no special platform (but burdens just like the air drop existing platforms) and costs relatively little in peacetime. The mine could work as torpedo mine upon contact and have a good radius of influence (most mines only hit ships directly above themselves).
The greatest disadvantage is the fact that relatively few torpedoes are in inventories today. Purpose-built self-deploying mines would likely be quite expensive per piece. The available quantities might be unsatisfactory when a war begins.



3) by air drop, with a glide phase
Combat aircraft payload and submarine ammunition storage would be scarce in wartime. To burden combat aviation and submarines with the mine laying mission might not be the best idea.
An air-droppable naval glide mine (using folding wings or a gliding chute - the technologies exist) can be deployed from dozens of miles away from the minefield location. The accuracy would be good enough.
A temporary suppression of long-range air defences (if nearby at all) and combat air patrols to keep enemy fighters away would be the only burden for combat aviation if military cargo aircraft are being used for this. Again, the mine-laying operation could be synchronized into a major air attack.

4) by submarine, with a special module
Air drop won't work if even only temporary and local air supremacy is too much of a requirement. Self-deploying submarine torpedoes are too few. What else?
An old solution is to build special mine-laying submarines that are normal submarines of appropriate range, but with a stretched hull. The additional hull space is used for dedicated mine-laying facilities. The quantity of mines can equal or exceed the quantity of torpedoes carried by the submarine.
The extra length and displacement doesn't cost much and reduces the effectiveness of the submarine in other activities only to a small degree.
This could be used for stealthy and affordable offensive mine laying unless the enemy protects his coastal waters with very effective anti-submarine warfare (ASW) assets.
It's noteworthy that modern submarine design - especially in the USA - incorporates modules that could be built for offensive mine laying. Nuclear submarines like those of the USN aren't first choice for mine laying in shallow waters, though.

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The often-heard complaint about the neglect of naval mine warfare in many NATO navies is in my opinion justified although there's some potential for secret stocks and capabilities.
Defensive naval mines can be employed with ease, offensive mine laying is relatively difficult. We could adopt existing military platforms (combat aircraft, cargo aircraft and submarines) or employ more specialized new platforms.
The costs for good preparations would be relatively modest for most offensive mine laying capabilities. Past conflicts have shown a pattern of peace-tie neglect and insufficient inventories of these relatively cheap munitions and mine warfare platforms.
We should benefit of military history and prepare adequately for the next time.

Sven Ortmann

P.S.: A nice link about the U.S. naval mine inventory, showing many (not all) different categories of mines in use today.
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4 comments:

  1. The reason the German mine deployment in 1940 turned out to be a "pulled punch" was because of interservice rivalry between the Kriegsmarine and the Luftwaffe. Goering refused to cooperate in the mining campaign and thus the Navy was forced to use seaplanes and destroyers in waters that were under the control of the British. Had the Luftwaffe committed as much effort to minelaying (and direct attacks on Channel shipping) as they did to attacking British aircraft production (which was never seriously degraded) the British would have been in serious trouble. After all, even large numbers of conventional contact mines could have broken the back of the overstretched British Navy.

    The US campaign of 1945 is a good indication of what could have been. Postwar studies demonstrated that the damage done to the Japanese economy by the mining campaign was greater than that done by the conventional bombing campaign, with far fewer losses of aircraft. In fact, NO aircraft were lost to enemy action while mining. Only 29 aircrew died while on mining missions, all of them due to operational accidents.

    This points up the fact that mining is invariably safer than direct attack because you lay the mine while the enemy isn't there. While modern air defenses may be able to cover large areas they cannot see over the horizon very effectively and the "attack" comes at a point well offshore. Even relatively clumsy aircraft like cargo planes and helicopters can mine many areas with little risk.

    This is especially true of the improvised bottom mines developed by the Americans (initially to mine river bottoms in Vietnam). Like the laser-guidance kits developed to give new life to old iron bombs, the mine fuses take a cheap conventional weapon and put it to a devastating new use. There's plenty of such bombs around, they're cheap to make, and no modifications are required to the aircraft. Only the fuse is exotic. It's a great way to get your air force involved in a naval campaign, especially for the US, whose Air Force goes out of its way to not know anything about naval warfare-shades of the old interservice rivalry that crippled the Germans in 1940.

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  2. James, ALL German military aircraft were under Luftwaffe control. The Kriegsmarine had no aircraft.

    The aircraft types weren't well-suited for naval mine laying anyway - the only ones that were suitably equipped in 1940 were a few dozen He111J and the Ju87 and Ju88 bombers, the Junkers models being the only bombers that were effective against shipping in regular attack.

    The Luftwaffe was an air force for the support of army operations in 1939-1941, anti-shipping was only improvised at that time.
    The scarcity of resources allowed for no diversion to anti-shipping capabilities at the expense of army support.

    The attacks on British aircraft production weren't very serious in 1940, maybe you meant attack on their airfields?

    Btw, the last that I learned about the Mk.71 naval mine fuze project of the USN is that the fuze was ready, but not put into production.

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  3. My understanding is that the Navy had operational control over all units assigned to work with it, in the same manner as the Royal Navy. Since these were mostly seaplanes, this was how many of the mines were delivered. The mines were compromised because the seaplane pilots got lost and dropped some of them in the wrong place-in a mud flat near Shoeburyness where ships did not generally go. Thus were the British mine experts able to wade out and recover them.

    The magnetic mines in question were intended to be dropped from German bombers. Indeed, the "land mines" dropped by the Luftwaffe in 1940 and 1941 were naval magnetic mines fitted with new fuses. The Luftwaffe was quite capable of handling the job but refused it.

    The Ju87 was used to attack Channel shipping after the Fall of France, but not to the extent it might have been. The British Navy genuinely dreaded the prospects of an all-out attempt to close the Channel, the more so since the RAF was as narrow-minded as the Luftwaffe and did not have any provision for systematic protection of Channel convoys. Fortunately, the Luftwaffe, as you point out, was obsessed with land warfare.

    The attacks on aircraft production facilities were small in comparison to what was going on over the airfields but that was my point: a relatively small diversion of resources towards minelaying would have had a tremendous impact, the more so since the minefields were area targets that could have been sown by night with a small chance of being intercepted by RAF fighters.

    Finally, the Mk 71 fuse may be the latest model, but the US has been modifying iron bombs into naval mines since Vietnam. It's not hard to do this. One wonders, in fact, why it isn't done more often.

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  4. Isn't an IED also a mine in a way? So if you have a stockpile of explosives, detonators, water-thight containers (standard blue plastic barrels I would suggest) and produce state of the art sensor equipment in wartime you can get most success by sudden and large waves of state of the art models yet unknown to the enemy. Sure, I'm not a great fan of enormous degrading stockpiles, but ready for upgrades munitions and raw materials.

    The article about the drug trafficking seems to offer also an option for naval minelaying by using low-tech low-observeable submersibles with very limited depth.

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