Against The Rising Sun!
- Life and Times of the 341st Bomb Group (M) -

"GLIP" BOMBING


        Within the 14th Air Force, the 341st Bomb Group was assigned the vital task of interdicting railroad and highway bridges in Indo-China.   This new undertaking was tackled with the same enthusiasm which prevailed when the Group moved to China.   But it required thought and careful preparation, for economical operation in China was most essential to sustained operations.   Gas and bombs were brought to China in dribbles by air transport after traversing thousands of miles of ocean and therefore could not be wasted.

      The bridges were singled out for concentrated attack.   This was due to the difficulties and time needed by the Japanese to repair them.   They were difficult targets, often located in valleys or canyons, easy to defend with anti-aircraft guns, smoke or cross canyon cables, and destroying the bridges was whole other matter.   The ratio of hits from both heavy and medium bombers from varying altitudes was very low.   Skip bombing was good, but a better method of busting bridges had to be devised if the bombers were not to be eliminated as an efficient and economical low-level weapon against enemy lines of communication... a job which the Group had continually done, despite its increased hazards.

      After theoretical considerations in the light of past experience, the 341st Group Commanding Officer submitted a new technique to the squadrons. This technique had been developed by the 490th Bm Sqdn, later nicknamed the 'Burma Bridge Busters'.   Hence forth, a combination glide and skip attack was to be used on all bridges, which method was subsequently labeled ‘glip’ bombing.

      It consisted essentially of a double or multiple glide approach, first a steep glide followed by a shallow glide.   The pilot approaches the target bridge along its longitudinal axis at an altitude of 1000-1200 feet.   When approximately 2000 feet from the target, he goes into a 30-35 degree glide, building up speed of 260-280 mph.   In this glide the pilot aims 50 feet in from of the target and continues to glide to an altitude of about 450 feet.   At this point the glide is abruptly decreased to 15-20 degrees.   While in this shallow glide the modified gun sight (N-6 or similar one) is lined up with the aiming point on the bridge.   The gun sight is preset before approaching the target area.   The angle set into the sight is that obtained from skip-bombing tables, with a correction for the angle of glide.   Bomb release is from an altitude of about 150 feet.

Glip Path diagram
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      Thus on December 11, 1944 the first ‘glip’ bombing attack was made in Indochina.   The target was the Hai Duong RR bridge on the Hanoi-Haiphong line, vital to the disposition of supplies and troops from the docks at Haiphong to the interior.   Flying thru intense and accurate machine gun and automatic weapons fire, the first six Mitchells successfully destroyed the bridge, but not without damage to themselves.   Tne Mitchell was badly hit and two crew members seriously wounded, nevertheless they succeeded in returning to base.   Another six Mitchells, learning enroute by prearranged signals that the primary target was out, attacked the alternate target, Phu Lang Thuong railroad and highway bridge.   Since ‘glip’ bombing was in the experimental stage, the latter Mitchells used a different sight setting and..... missed.

      That was the difficulty of China operations.   "Practice" was not practical.   Bombs and guns could not be spared for such purposes in a theatre that not infrequently postponed actual combat operations because of a shortage of bombs or gas or both.   Experience had to be gotten, and only one way, the hard way..... in battle!   And particularly praiseworthy is the fact that in the perfection of ‘glip’ bombing, the airman continually exposed themselves to concentrated enemy fire, the type of fire that as a rule only fighters with their greater speed were intended to encounter.   That the enemy’s small arms, machine gun and automatic weapons defenses, strategically disposed around bridges for maximum effectiveness against any attack ove the bridge, was ‘deliberately’ encountered by the medium bombers is evident in the method of attack.   The altitude of attack alerted the defenders or at least the attack of the first aircraft did.   Thereafter, each aircraft was met by the full fury of enemy fire as it made its individual run.   Nor could the target be attacked from any angle, on the deck, as in skip bombing to achieve surprise.

      The effectiveness of the attack depended upon an approach along the axis of the bridge, thus any attack was from one or the other end of the bridge.   The double glide angles of the attack compensated somewhat for this headlong flight into the jaws of the enemy.   Nevertheless to successfully ‘glip’ a bridge, a deliberate passage thru hell, the concentration of small arms, machine gun and automatic wapons fire, and sometimes blossoming white puffs of time fused mortar shells as they exploded in a blanket over the target, was essential.   The amount of enemy opposition was not the same at every bridge, but its intensity could be relied upon at the big ones, like Phu Lang Thuong, Hai Duong, Yen Xuang, Phu Ly, Ninh Bibh, Dap Cau, Ba Trung, Song Rang, etc., and some opposition was likely at any bridge attacked.   In addition was the ever present hazard of being caught on the deck by enemy fighters hovering overhead.

      But the airmen did not falter.   With sustained gallantry they trained against the enemy, they practiced on the enemy, and the became experienced bridge busters at the expense of the enemy’s lifeline overland.   On 24 operational days during a three month period the 341st Bomb Group relentlessly pursued its objective, destroying a total of 21 bridges and damaging 17.   ‘Glip’ bombing raised the efficiency of the Group’s bridge busting from 15.5 tons to 7.5 tons per bridge destroyed, an Army Air Forces record!   Toward the end of this period near perfection was reached… February 27, 1945 four bridges were destroyed at the low cost of 2.94 tons per bridge, March 5, 1945 a total of 6 bridges were destroyed and 2 heavily damaged due to the ‘bridge blitzing’ with an average expenditure of 4.32 tons.   Thus ‘glip’ bombing proved itself an efficient, economical method of attack where, in the China theatre of limited supply, it meant more sorties against and greater damage to the enemy.

      However, the cost to the Group was not light.   Men could not charge into withering fire as did the glip bombers and expect to come out unscathed.   Priceless lives were lost, men were injured, ships were lost.

      Flying, in itself, in China is dangerous.   The terrain is rugged and jagged mountains had to be traversed.   Weather is an elusive, unpredictable thing in Chaina, and attacks had to be run when there was a break.   While on a mission, weather sometimes "socked in" at the base, and at times targets were attacked under ceilings of less than 2000 feet.   All was not fair where weather was concerned.   Yet a fighting spirit prevailed, despite the ack-ack, the terrain, the weather.   Mitchells on single engine cork-screwed their way back thru mountain ranges over which they couldn’t fly, flew over or thru the weather.   The job was a tough one, but was well done.

      That the enemy subsequently gave up their land corridor did not astonish the 341st Bomb Group.   Some of the sturdy steel and concrete bridges built by French engineers were like Humpty Dumpty, and once they fell, all of Emperor Hirohito’s little men couldn’t put them back together again.

      The 341st Bombardment Group received the Distinguished Unit Citation for developing and using the glip bombing technique against enemy bridges in Indochina.