The Solomons Campaign: Cactus Air Force and the Bismarck Sea

Thus far, and not surprisingly so, the conversation has focused on the naval forces – afloat and ashore, at work in the Solomons. Today we go a wee bit joint and talk about land-based air and its contribution.

We are all (or should be) pretty familiar with the inter-service rivalry that sprung up pre-war between the Navy and the (upstart) Army Air Corps. Claims and assumptions flew thick and heavy in the open press and behind War Department doors over what each service could do and the relative utility of the (then) fragile motorized kites called aircraft. Mitchell’s demonstration off Vacapes in 1921 served to fan the inter-service flames – but the facts are that it did force Navy to look harder at aircraft in an anti-ship role. On the Army Air Corps side, there was a push on for long-range bombers, leading to the B-17 and later the B-24, and several medium bombers (notables of which were the Douglas A-20 Havoc, the North American B-25 Mitchell and Martin’s B-26 Marauder) which at the time, fell into a “what do we do with these?” train of thought. As the war opened, the record of land-based bombers was, well, spotty. There were isolated instances of note – Doolittle’s raid being the most visible (technically, not land-based), but for the most part, the heavy bombers were still almost a year away from making their presence felt in Europe and in the Pacific, had been more noted for being caught and destroyed on the ground in the Philippines after Pearl Harbor was attacked. While present in the opening stages of Midway, the heavy bombers tried mightily to sink ships from high altitude and only succeeded in destroying lots of plankton and fish(and this, by the way, despite the use of what was then precision targeting via the Norden bombsight, developed originally to attack ships from high altitude), while the B-26’s and other Midway-based aircraft were pretty well decimated, like most of their carrier counterparts, by Japanese carrier-based air and AAA.

As was the case throughout the theater, though, there was some innovative thinking taking place and the sting of Allied land-based air would soon be felt… – SJS

It is early 1942 and you are inbound to Douglas MacArthur’s staff as his new air commander, commanding the Fifth Air Force and the Allied Airforces in the South West Pacific. The dilemma you are faced with is that the allies have been in retreat in the face of the Japanese onslaught which has seen great swaths of Asia fall into their possession. You, in turn, are to meet that formidable force with a rag-tag group of survivors gathered from around the Philippines and the rest of the theater, now based in Australia. Your counterpart over in the Navy is exceptionally busy as well, struggling to meet the threat with what was still afloat from Pearl Harbor and subsequent attacks (fortunately the carriers survived) and some land-based air. Most of it, however, is out of your territory and besides, controlled by the Navy.

You think about where and how to hit the enemy to effect the most damage, and like your Navy counterparts, deduce that the Achilles heel in the Empire’s far-flung lines of support is shipping, merchant shipping. The thousands of island garrisons, from the biggest at Rabaul to the smallest outcrop of coral and volcanic rock were all heavily dependent on supply from the sea. In later parlance, it would be “a target rich environment.” Problem is, pre-war tactics have proven abysmal when applied in the real world. High altitude precision bombing wasn’t working against a maneuvering target and attempts to replicate at lower altitudes ran into swarms of fighters and heavy flak from escorts. What do you do?

If you’re George C. Kenney, you do the following. Before departing for the Pacific, you determine that because of the ranges involved you need long-legged fighters to provide some protection for the medium- and heavy-bombers you intend to unleash. So you get “Hap” Arnold to assign 50 P-38s with 50 pilots from the Fourth Air Force to your new command in the Pacific, making sure that a certain aggressive young lieutenant who had looped the Golden Gate, Richard Ira Bong, would be one of those pilots.

You also request some 3,000 parafrag bombs to be sent to Australia, where you think they might come in handy against the Japanese, especially in airfield and port services denial. While en route to Australia with your aide, Major William Benn, in July, you discuss the shortcomings of pre-war bombing tactics and turn to low-altitude bombing. During a layover at Nandi in the Fijis, you requisition a Martin B-26 Marauder bomber and test a theory–that a bomb could be made to skip along the water like a stone. Your theory proves to be correct and the technique of skip-bombing is born.

Upon arrival in theater you institute several plans that would have a revolutionary effect on combat operations. To begin with, you take the rudimentary transport aircraft under your control and layout the beginnings of air transport support for ground operations. You assemble an air force out of damaged aircraft on hand and requisition aircraft not in favor in Europe (and therefore available) – aircraft like the B-25, A-20 and P-38. You turn over your tactics and operational planning and execution to the likes of leaders like:

• Maj William Benn, CO of the 63rd Bomb Squadron who developed and refined the art of skip-bombing. He experimented with different bomb sizes, timed fuses, and approaches to targets. He led one skip-bombing raid with a half-dozen B-17s at low altitude and sent six enemy ships to the bottom. According to Kenney, “Skip bombing became the standard, sure way of destroying shipping, not only in Bill’s bombardment squadron but throughout the Fifth Air Force.” In skip bombing, the bombing aircraft flew at very low altitudes (200 to 250 feet above sea level) at speeds ranging from 200 to 250 miles per hour. They would release a “stick” of two to four bombs (usually 500 or 1000-pounders) equipped with four- to five-second time delay fuses at a distance of 60 to 300 feet from the side of the target ship. The bombs would “skip” over the surface of the water in a manner similar to stone skipping and either bounce into the side of the ship and detonate, submerge and explode under the ship, or bounce over the target and explode as an airburst. All outcomes were found to be effective.
• Maj “Pappy” Gunn who had already displayed a legendary skill at aircraft maintenance on a shoe-string. Gunn developed a package of four .50-caliber machine guns for the nose of A-20 light bombers. This impressed Kenney. He directed Gunn to “pull the bombardier and everything else out of the nose of a B-25 medium bomber and fill it full of .50-caliber guns, with 500 rounds of ammunition per gun.” Kenney said, “I told him I wanted him then to strap some more on the sides of the fuselage to give all the forward firepower possible. I suggested four guns in the nose, two on each side of the fuselage, and three underneath. If, when he had made the installation, the airplane still flew and the guns would shoot, I figured I’d have a skip bomber that could overwhelm the deck defenses of a [Japanese] vessel as the plane came in for the kill with its bombs. With a commerce destroyer as effective as I believed this would be, I’d be able to maintain an air blockade. . . anywhere within the radius of action of the airplane.”

• Maj. Ed Larner. He and his “commerce destroying” squadron had become expert at skipping bombs into ground targets at low altitudes and strafing the nose- and side-gun-firing .50 calibers. Kenney recalled, “I saw a couple of them practicing on the old wreck on the reef outside Port Moresby. They didn’t miss. It was pretty shooting and pretty skip bombing.”

These efforts led to signatory events, such as the Battle of the Bismarck Sea in March 1943:

(high res here)

In early 1943, the Japanese army in New Guinea launched an offensive with the 51st Japanese Division advancing on Kanga Force – the Australians holding the airfield at Wau. To achieve this objective, the 51st required reinforcement from Japanese forces in Rabaul. These reinforcements were to sail around New Britain through the Bismarck Sea and across the Huon Gulf to Lae.

February 19th, allied forces intercepted message traffic indicating the Japanese were marshalling their forces and preparing to embark a New Guinea-bound troop convoy from Rabaul. Almost 7,000 Japanese infantry and marines were to travel to New Guinea in eight crowded troop transport ships. Surveillance patrols increased and the Allies readied their air forces.

By early March, a combined US/Australian force of 154 fighters, 34 light bombers, 41 medium bombers and 39 heavy bombers had been assembled. At 1500 local on 1 March a patrolling B-24 Liberator spotted a convoy through a break in the clouds. US heavy bombers were immediately dispatched to attack, but failed to find the convoy due to heavy cloud cover. The following day brought clearer skies allowing a progression of attacks from B-17s attacking from medium and low altitude, including using ski-bombing techniques. Several hits were scored with one sinking claimed at the loss of one B-17 due to fighters.

The following day, March 3rd, the convoy was within range of the RAAF bomber squadrons at Milne Bay in Papua and they attacked and they were joined later by the US and Australian squadrons from the vicinity of Port Moresby (they were held on the ground due to weather). The first attack was made by RAAF Beaufort torpedo bombers. They did not score any hits but were followed closely by 13 RAAF Beaufighters who inflicted damage with low level strafing runs until B-25 Mitchell’s of the 5th USAAF attacked from altitudes of 2,000 to 3,000 feet.

The nexus of the attack though came with the modified B-25s which had been practicing skip-bombing – the impact was devastating as they claimed 17 hits. Above them , B-17s bombed the convoys from high altitudes, disrupting the convoy and making defensive fire difficult at best. By this time half of the transport ships were lost or are sinking.

The final phase of the battle saw a combined attack with A-20’s and B-25’s at low level while counter-air operations were conducted against the Japanese airfield at Lae to thwart attempts at air cover for the convoy. All told, another 15 hits were claimed. That evening, US Navy torpedo boats sank the remaining transport. By dawn of March 4th, all eight transports were sunk along with four of their escorting destroyers (the other four were badly damaged). Out of 6,900 troops who were badly needed in New Guinea, only about 800 made it to Lae. Few were battle ready and most had lost their weapons and equipment.

(Note the inbound bomb just ahead of the skip-splash)

Maverick tactical innovators driving field modifications and employment of weapon platforms and systems in ways unforeseen during the pre-war period – certainly driven by a measure of desperation (as someone once said the prospect of a hanging tends to focus one’s thinking…). Still, the background had to be there before the war, renegade thinking though it was. And as we have increasingly seen in the various engagements throughout the Solomons to date, pre-war thinking and tactics haven’t necessarily borne the fruit imputed to them.

Oh yes – and Bismarck Sea wouldn’t be the last the Japanese felt of the Cactus Air Force either…

(cross-posted at USNI blog)