Only Thorncrofts were able to meet the Royal Navy’s tight specification for the CMB. This is the 55-foot version.

The CMB was conceived to attack enemy vessels in their own harbours. This was their finest moment—and their swan song.

The raid on the Russian naval base at Kronstadt on August 18, 1919, was the highlight, and the swan song, of Coastal Motor Boat (CMB) actions in World War 1. It demonstrated that boldly and skilfully handled CMBs could achieve a great deal, but opinion in the Royal Navy regarding their fighting value remained split. In the decade following the end of the war, they gradually disappeared from the navy.

The CMB was conceived in 1915 with the idea of having fast torpedo-carrying motor boats to attack enemy vessels in their own harbours. As they were intended to be carried in a cruiser’s davits to the scene of operations, their total weight was restricted to 41/2 tons. It was a tight specification, and only one firm, Thor­nycrofts, were able to meet it. They produced a 40-foot boat capable of 34knots, carrying an 18 in. torpedo in a trough at the stern. The torpedo was fired, tail first, by a cordite charge. The boat was aimed at the target, turning away immediately the torpedo was fired. High speed was necessary for the boat to get out of the way of the torpedo.

After some experience with the 40 ft. type, the Admiralty decided that a larger boat would be useful. A 55 ft. CMB carrying one or two torpedoes and four Lewis guns was designed. Too big to be carried in davits, they had to proceed to the scene of operations under their own power, or in tow for big distances.

The CMBs never achieved their main purpose — an attack on the High Seas Fleet anchorage. They did see some action off the Belgian coast and in the Dover Straits against German destroyers and patrol craft.

The Armistice of 1918 brought an end to fighting in Western Europe. But in the Baltic area, there was a complicated imbroglio going on. Britain and France were supporting the newly created Baltic states, Poland, Finland, Estonia and Lithuania against the Bolsheviks, as well as assisting the White Russian Army.

Rear Admiral Sir Walter Cowan had been sent to the Baltic early in 1919 to command a force of light cruisers and destroyers holding the Russian Fleet at Kronstadt in check. Against his 6in gun cruisers the Russians could muster the 12in. gun dreadnought Petropavlosk, the 12in. gun pre-dreadnought Andrei Pervosvanni, and the 8in. gun armoured cruiser Oleg. Luckily, they showed little initiative.

There were no CMBs attached initially to the British force. The first boats to arrive in the Baltic were CMBs Nos. 4 and 7. These two 40 ft. boats, under the command of Lieutenant Augustus Aga, R.N., were sent to carry out “courier” duties for the In­telligence Service, and did not come under Cowan’s command. Unarmed, their task was to ferry agents in and out of the Bolshevik-held territory. Their crews wore civilian clothes, but carried uniforms to don if in danger of capture.

Agar established a base at Terrioki, on the north shore of Petrograd Bay. From here the boats ran by night to a point near Petrograd to land or pick up their passengers. Lt. Agar was not a man to accept a passive role easily. Reporting his arrival to Rear Admiral Cowan at Biorko, he requested to be supplied with tor­pedoes. Cowan reluctantly agreed to supply these, on the understanding that if they were carried the boats would fly the White Ensign and the three-man crews would be in uniform. Two 18in. torpedoes then were sent to Terrioki.

There was some unrest in Kronstadt among the sailors who were generally unsympathetic to the Bolsheviks. At the beginning of June, Fort Krasnaya Gorka on the south shore of the bay revolted against the Bolsheviks. To bring the rebels to heel, the Petropavlosk and the Andrei Pervosvanni bombarded the fort. An­choring where the forts guns would not bear, they began to leisurely lob in 12in. shells.

Agar felt that if the fort could hold out it might induce the sailors in Kronstadt to rise. But how long could they stand this bombardment? Orders forbade the boats to take aggressive action. A signal to London explaining matters drew a reply to the effect that the boats were to be used for intelligence purposes only. However, a rider was added that no action was to be taken without the consent of the SNO Baltic. Agar pondered this last sentence. The Rear Admiral was too far away at Biorko for immediate consultation. So Agar decided to take his approval for granted. He began to plan an attack on the two battleships.

Early on the morning Friday June 1, White Ensign flying, he set out in No. 7 to reconnoitre the battleships. At 0200 hours, he located the two battleships at anchor, with a destroyer guard. An at­tempt at attack was prevented by a sudden engine failure. Unable to reach torpedo firing speed, there was nothing to do but return to Terrioki.

On the night of June 16, Agar had another go, taking both boats. Rounding Tolbukhin lighthouse No. 7′s propeller struck some heavy floating object. The impact sheared the propeller shaft. So there was nothing for it but to return to Terrioki with the cripple in tow.

Despite two failures, Agar was deter­mined to carry on. Next night he set out again in No. 4. Sailing from Terrioki at 2230 hours, he set a course west beyond Tolbukhin lighthouse. Proceeding in rather heavy seas, he went about three miles to the west before circling round to approach the fort — to make it appear that the attack had come from Biorko.

Reaching the anchorage where the battleships should be, Agar failed to find them — they had returned to Kronstadt. But he did locate a four-funnelled cruiser anchored with a guard of four destroyers, a sloop and a torpedo boat. This was the Oleg, which had replaced the battleships. No. 4 slipped between the destroyers and prepared to attack. At this critical point Sub. Lt. Hampsheir, in preparing the torpedo, accidentally fired the charge. Luckily, the two clamps were still on and the torpedo did not leave the trough. But it meant a new charge had to be fitted. Working in the dark in the rolling boat only 700 yards from a guard destroyer, it took 20 minutes to fit the charge. Luckily, the CMB remained undetected.

The new charge fitted, Agar swept in to attack. Increasing speed, he slipped through the guard ships. Approaching the Oleg at full speed, he fired his torpedo at a range of 800 yards, turning away to starboard afterwards. As No. 4 sped away, her crew saw a white fountain of water leap up the Oleg’s port side just abaft the forward funnel. The explosion was the signal for the Russian ships to open a wild, heavy fire at the CMBs wake. Most shots fell wide, but three heavy shells fell close enough to throw up No. 4′s stern and cause her to temporarily reduce speed.

Agar’s last sight of the Oleg showed her settling by the head, heavy black smoke pouring from her funnels. The torpedo had been fired at 0005 hours. By 0030, the CMB was far enough away to reduce speed and set course for Terrioki, which she reached at 0145.

The sound of the firing was heard at Biorko. No cause could be ascribed for it until a signal was received from Agar reporting the events of the night. Later a plane took off from the improvised landing strip at Biorko and flew over the area and this reconnaissance revealed the Oleg lying on her port side near the north-east end of Kotlin Island. It also revealed that the blow had come too late for Fort Krasnaya Gorka. The Red Flag was once more flying over it.

But if this successful attack was too late to save the fort, it had the effect of setting the Rear Admiral thinking. He sent a signal to Lt. Agar to come over to Biorko. When Agar arrived, Cowan discussed with him the feasibility of a raid on Kronstadt itself to neutralise the two battleships. After due consideration, Agar considered it was possible. A signal was then sent to the Admiralty, requesting a flotilla of CMBs, a request duly granted.

A flotilla of eight boats under the command of Commander Dobson, R.N., set out in tow from the CMB base at Osea Island. One — No.67 — was lost en route, the others reached Biorko on August 2.

They were the 55ft. boat, armed and commanded as follows:‑

No. 31 Commander Dobson and Lt. McBean 2 torpedoes

No. 79 Lt. Breaner 1 torpedo

No. 88 Lt. Dayrell-Reid 2 torpedoes

No. 24 Lt. Napier 1 torpedo

No. 72 Sub-Lt. Bodley 1 torpedo

No. 62 Lt.-Cmdr. Brade 2 torpedoes

No. 86 Sub-Lt. Howard 2 torpedoes

The cruiser Vindictive, which had been converted for aircraft carrying, took on the task of acting as mother ship to the flotilla. No time was lost in getting down to arranging a plan for action, for it was desirable to strike before the news of the CMBs arrival leaked through to Kronstadt. The earliest moonless nights would be between August 17 and 24. A plan of action was drawn up to be put into operation as soon as opportunity arose.

It was decided that the best way would be for the boats to attack in two groups of three, with a short interval between attacks for the first group to clear the harbour. The seventh boat would deal with the guard ship. Lt. Agar would pilot the boats through the line of forts guar­ding the North Channel. While the raid was on, he would lie outside the adjacent military harbour to attack any craft which might attempt to come out. To assist the boats in achieving surprise, an air raid would be mounted by the Vindictive’s mixed bag of planes, to start just before the boats entered the basin.

The actual date of the raid was fixed by the weather. On August 15, strong westerly winds resulted in the tideless waters of the Baltic being raised three feet in Petrograd Bay. By the 17th, this was a bonus not to be missed. On that afternoon, a reconnaissance flight was made over the basin, Commander Dobson going along to have a view of his targets.

The first group of boats would go for the priority targets, the Petropavlosk, the Andrei Pervosvanni, and the submarine depot ship Pamiat Azova. The second wave would repeat the attack if they failed. If the first wave succeeded, the second would attack the dry dock gates and the mine laying cruiser Rurik. She to be attacked last as her 300 mines would make a very unpleasant explosion.

At 0030 hours that day, the boats from Biorko rendezvoused with Lt. Agar in No. 7 off Inonini Point. The services of two 2 local smugglers as pilots had been obtained by suitable payment. One went in Agar’s boat, the other with Commander Dobson.

The flotilla moved off at 20 knots, a speed at which the CMB’s engine were not too noisy. Agar could see the spray from No. 24 behind him, but soon lost sight of the other boats. As they approached the line of forts, their wash was sighted and a spasmodic fire from machine guns and light artillery was opened on them. The forts did not, however, use searchlights. Agar’s pilot elected to pass over the submerged concrete breakwater about the middle of the chain. No damage was sustained from the fire of the forts, but at this time the force suffered its first set­back. Lt. Howard’s No. 86 had an engine breakdown just before reaching the forts and had to be left behind.

As the boats began their turn to star­board to pass round the east end of Kotlin Island, the sound of anti-aircraft guns and the beams of searchlights indicated that the air raid was underway and the at­tention of the port’s defences well oc­cupied. Arriving off the entrance to the basin, Agar found that the boats of the first wave had already arrived. Not long after sailing, the three boats led by Dobson had got so far over to starboard that they found themselves close to the north shore of Kotlin Island. Their local pilot turned away to port and passed through a gap in the breakwater closer inshore than Agar. This was made possible by the three-foot increase in depth. As a result of this, the boats arrived a little ahead of schedule.

The first boat to go in was No. 79 Lt. Bremner, at 0140 hours. He was equipped with wire-cutting gear and guncotton charges to deal with any boom or chain, but found no obstructions. No. 79 was able to accelerate across the basin and fire her torpedo at the Pamiat Azova. The noise of the aircraft engines helped to drown the noisy CMB engines and complete surprise was achieved. The explosion of the torpedo was the first indication to the Russians that the attack was on.

Dobson’s No. 31 followed No. 79 but swung away to port to attack the bat­tleships. As he did so, the defences began to come to life in the harbour. The basin was swept by machine-gun fire and searchlights were exposed. No. 31 was able to get a good shot and both tor­pedoes struck the Andrei Pervosvanni. By now the basin was like the proverbial hornet’s nest. The last boat, No. 88, found herself under heavy fire. Sub-Lt. Steel was firing back with the Lewis gun as Lt. Dayrell-Reid swung the boat round to port. From behind his gun, Steel suddenly realised that the boat was swinging too far to port for her shot at the battleships. A quick glance revealed that the lieutenant was slumped across the wheel, shot in the head.

Abandoning the Lewis gun, Steel managed to get the body off the wheel and brought the boat back to starboard. He just managed to reach the aiming position and fire the torpedoes before the boat was too close.

One torpedo struck an anchor chain but the other struck the Petropavlosk under the forward turret. The CMB was so close that, as she turned away to port, water and debris from the explosion fell around her. Steel took No. 88 to join No. 31 in the waiting area at the south end of the basin, and both boats then left the basin. For some reason, No. 79 was late leaving, with disastrous consequences.

The attack by the first wave had been lucky. Now began a series of misfortunes. The first was to No. 24. As planned, Lt. Napier attacked the guard ship, the destroyer Gavril anchored outside. For some reason, the torpedo missed and No. 24 was struck by a shell which split her in half as she turned away.

The second wave had already had the misfortune to lose the services of No. 86. Fifteen minutes after the first wave had gone in, Lt. Brade’s No. 62 swung into the basin and collided with No. 79, which was just coming out. He struck No. 79 on the port side, almost cutting her in half. With no reverse gear, No. 62 could not back out. Instead Brade kept her going ahead and managed to turn so that he pushed No. 79 ahead of him out of the basin. Lt. Lt. Bremner ordered his two-man crew to clamber aboard No. 62 while he set the fuses of the guncotton charges to ensure No. 79′s destruction. Shortly after he had clambered aboard No. 62 and Brade had got clear of No. 79, the latter blew up.

Since he still had his torpedoes, Brade decided to have a go at the Gavril. This vessel seemed to have a charmed life for, once again, the torpedoes missed her. As No. 62 was heading away, a shell struck her. It completely wrecked the engines and holed the boat so badly that she sank shortly afterwards.

The last boat, Sub-Lt. Bodley’s No. 72, entered the basin and headed for the dry dock, intending to torpedo the gates. She got halfway there when a shell splinter struck the cockpit. Nobody was hurt, but the splinter struck and distorted the torpedo-firing mechanism, jamming it. Unable to fire his torpedo, Bodley turned away and sped out of the basin. Running back round the eastern end of the island, he passed the forts and found the disabled No. 86. A towline was rigged, and Bodley towed her to Terrioki.

Agar’s No. 7 was the last to leave. Since no craft had come out of the other basin, No. 7 still had her torpedo, and Agar decided to use it on a clump of small craft lying inside this basin. It exploded doing considerable damage. At about 0210 hours, Agar set course for base.

With the forts now thoroughly alerted, the CMBs would have had an un­comfortable passage. They were helped here by the aircraft, which carried out a series of low flying attacks on the forts. These attacks, together with the use of smoke floats, enabled the boats to get past the searchlights and shellfire without damage.

Rear Admiral Cowan had provided a backing-up force of light cruisers and destroyers at the head of the bay, which had moved in after the attack started. They met No. 31 and No. 88, and the wounded Lt. Dayrell-Reid was transferred to the Delhi’s sickbay where he died a little later. The surviving boats returned to Terrioki where they refuelled and except for No. 7, returned to Biorko.

A reconnaissance flight over the basin later in the day revealed that the Pamiat Azova was lying on her port side, and the two battleships were sitting on the bottom. They could only sink about three feet but were going to be out of action for a long time. The cost for this had been three CMBs lost, four officers and four ratings killed, and three officers and six ratings taken prisoner. Amazingly, despite the difficulties of taking off and landing on the improvised airstrip at night, there were no aircraft casualties.

Cmdr. Dobson and Sub-Lt. Steel were awarded the VC. Lt. Agar was also awarded a VC for his attack on the Oleg, but as this was cloaked in security it has been called “the mystery VC”. Several D.S.O’s, D.S.G.’s, D.S.M.’s and D.F.C.’s were also awarded.

Although the CMBs disappeared from the Navy, one of the boats engaged in these events has survived. CMB No. 4 was acquired by her builders, Thornycrofts, and preserved in their yard. When the boatyard was closed down, she was handed over the Imperial War Museum. Her hull is now in storage awaiting suitable exhibition space.

Admiral Bacon, in his book on the Dover Patrol, summed up the verdict on CMBs considering that they had great potential value “provided their general unreliability and fact of special use was recognised.”