Operation Flintlock – Sixty-seven Years Ago

On this day in 1944, a massive armada began landing US Army, Navy, and Marine Corps personnel on the islands of Kwajalien Atoll, in the central Pacific Ocean.  Allies used the code name “Flintlock” for the operation.  Over the next seven days, the force dislodged, and for all practical purposes annihilated, the Japanese garrison and gained control of the world’s largest coral atoll.  As result, the US drive across the Central Pacific gained another base, extending land-based air coverage out towards the next objective – the Marianas Islands.

Map of Kwajalein

A landing force mostly comprised of the Army’s 7th Infantry Division landed on Kwajalein Island (on the southeast tip of the atoll in the map above) with the objective of an airfield there.  Meanwhile the 4th Marine Division landed on the large island concentration of Roi-Namur in the north to secure Japanese facilities, including another airfield, there.  The somewhat seasoned 7th Infantry had seen prior service in the Aleutians, but was making its first landing in the warmer Central Pacific.  Flintlock was the 4th Marine Division’s first landing (first of four within the next thirteen months!)  Both groups committed just over 20,000 combat troops each.  Defending the Atoll were about 8600 Japanese.

Initial landings on December 31 occupied lightly defended minor islands in the Atoll, to secure landing craft passages for the main landings and to provide firing positions for divisional artillery batteries.  The main landings started on February 1.  After some confusion with landing craft, the Marines secured the beaches at Roi Island and moved inland with deliberate speed.  Remarkably within 27 hours the Marines had secured the major islands in the north, at the cost of 195 killed and 545 wounded.

Clearing a Pillbox on Kwajalein

Observers described the Army’s landings in the south as nearly flawless, among the best conducted in the entire Pacific War.  Terrain constricted movement, and the 7th Division slugged through several pillbox defense complexes over the next few days.  By February 4, save some mopping up, the island was in American hands.  The Army division lost 177 killed and 1037 wounded.  The two forces completed Flintlock with a few additional landings, but by February 8, garrison troops arrived to convert Kwajalein into a major new American base.  Of the entire Japanese garrison (including some Korean laborers), only 265 surrendered.

Aftermath of Battle - Sherman transports a Japanese Tank

The “lessons learned” from Operation Flintlock are many in number.  But three deserve discussion here, as they pertain to military operations (and other endeavors) today as they did then.

First, prior to the operations, the Marines and Army troops practiced… and practiced… and practiced.  The 7th Infantry setup mock Japanese bunker complexes on Oahu, Hawaii based on experience at Tarawa.  These drills paid off during the landings, as the troops moved off the beach, and proceeded to reduce enemy defenses.  Smart, directed training offered a substitute for experience in the Kwajalein landings.

Second, coming behind the long running campaign at Guadalcanal and the nearly disastrous battle of Tarawa, the US Army, Navy, and Marine Corps proved rather adaptable.  Instead of differing doctrine changes to those back in the states, commanders and staff in the combat zone worked out new ways to work around enemy defenses.  Naval ships moved closer inshore to provide gunfire support, and in heavier quantities than before.  Aviation assets learned to provide pinpoint close air support.  The services learned beachhead traffic management.  Logisticians defined “combat loading” procedures.  And the list goes on.  In short, the Americans “learned” in the field and applied those lessons directly to the next action.  This aspect of the “American way of war” continues to this day, with a force which time and time again proves adaptable to the situation.

Lastly, flying in the face of nearly two-hundred years of inter-service rivalry, the Army-Navy-Marine team worked as … well … a team!  At Kwajalein, a Navy Admiral in charge of the operation brought a ground force under command of a Marine general which included a full Army Division (and then some).  Flying long range cover for the entire operation were some fourteen squadrons from the Army Air Forces (gotta work in the USAF somehow here!).  Flintlock was a true joint operation.

Today Operation Flintlock is but a footnote to the larger history of World War II, sandwiched between Tarawa and the “Great Marianas Turkey Shoot” in the books.  Of note, historian S.L.A. Marshall conducted one of his first “oral histories” compiling accounts directly from the soldiers in action.  The resultant work, published as Island Victory: The Battle of Kwajalein Atoll, stands as a landmark for the practice of military history, but also one of only a few studies of the action outside official histories.

I would encourage those interested in this early “joint” operation to read the Army “Green Book” covering the campaign or Volume VII of naval historian S.E. Morrison’s History of United States Naval Operations in World War II.   Marshall’s book, while important, is like many of his works – a labor to read!


5 thoughts on “Operation Flintlock – Sixty-seven Years Ago”

  1. Casualties seem remarkably light on the US side in this operation. <400 dead / ~2000 wounded for both Army and Marine Corps? That's really amazing for an amphibious assault against prepared defenses. Wouldn't you normally expect much higher losses, especially when attacking with only a 4:1 ratio?

    1. Actually the Japanese did not invest as much to defend Kwajalein as at Tarawa, or say later at Iwo Jima. Several reasons for this, but for for brevity, they all boil down to changes in strategy. Further, Kwajalein was the last “atoll” objective, with a narrow landmass. The Marianas, Palaus, and Bonins were much larger tracks with the option to defend in depth.

      Plus, as alluded to above, the US forces engaged entered the fight at a high state of readiness – lots of lead time to train.

  2. On 16 January 1944, the USS Yorktown (CV-10) exited Pearl Harbor to support an amphibious assault—-Operation “Flintlock,” the Marshall Islands operation. Her task group, Task Group (TG) 58.1, arrived at its launching point early on the morning of 29 January 1944, and its carriers—Yorktown, Lexington (CV-16), and Cowpens (CVL-25)—began sending air strikes aloft at about 0520 for attacks on Taroa airfield located on Maloelap Atoll. Yorktown’s Air Group 5 (which included VB-5’s SBD-5 Dauntless flown by my father) was assigned this task. Throughout the day, her aircraft hit Maloelap in preparation for the assaults on Majuro and Kwajalein scheduled for the 31st.

    On 30 January 1944, Yorktown and her sister carriers shifted targets to Kwajalein to begin softening up one of the targets itself. When the troops stormed ashore on the 31st, Yorktown aviators continued their strikes on Kwajalein in support of the troops attacking that atoll. The same employment occupied the Yorktown air group during the first three days in February.

    On 4 February 1944, the task group retired to the Fleet anchorage at recently secured Majuro Atoll.

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