Interwar Navy-Marine Corps Integration: A Roadmap for Today

CNO’s Design Week

By Capt. Jamie McGrath (ret.)


In his FRAGO 01/2019: A Design For Maintaining Maritime Superiority, Chief of Naval Operations, Admiral Michael Gilday calls out three focus areas: Warfighting, Warfighters, and the Future Fleet. The CNO declares that “Together with the United States Marine Corps, our Navy is the bedrock of Integrated American Naval Power.” This level of USN/USMC Integration was last seen at the end of WWII. The path to that level of integration blazed in the interwar period provides a blueprint for integrating today’s Navy and Marine warfighting and warfighters.

Admittedly, the crucible of a world war played a significant role in forging the Navy-Marine Corps team into a virtually unstoppable amphibious juggernaut that systematically took over Imperial Japan’s Pacific empire. But the foundation for the integrated team began in the interwar period with three interrelated efforts: large-scale Fleet Problem exercises, which included amphibious operations, constant wargaming at the U.S. Naval War College, and all-out effort at the Marine Corps schools to develop and refine amphibious doctrine. Although not initially coordinated, by the mid-1930s, these efforts all focused on the plan to defeat Japan, commonly referred to as War Plan Orange.

Preparing for War

The Fleet Problems, the interwar equivalent of today’s Large Scale Exercises (LSE), allowed fleet and ship commanders to experiment and practice with their weapons platforms at both unit and fleet-level formations. This allowed the development of doctrine and the full exploration of the new capabilities as they joined the fleet. Fleet Problems even exercised future capabilities with the interwar years’ version of Live, Virtual, and Constructive training – the simulation of capabilities with surrogate and constructive forces. Following the Fleet Problems, robust conversations and formalized after action debriefs, which included dozens of senior commanders and junior officers of the fleet, critiqued the performance. The Fleet Problems identified some enduring lessons that can guide development of warfighting today: innovation requires time to mature; exercises and wargames should not be confused with reality; surrogates should not be mistaken for actual capability; annual large scale exercise foster openness, flexibility, and frankness; familiarity with tactics and operational concepts leads to internalization of these ideas; and the role of the Fleet Problem is to explore ideas, not necessarily technology; and candid critiques must be done immediately afterward.1

The cost of the Fleet Problems, both in dollars and wear and tear on the fleet, meant they occurred only annually. Unconstrained by these costs, the Naval War College took the lessons from the Fleet Problems and incorporated them into a vast series of wargames. These wargames were also unconstrained by predetermined conclusions. Throughout the 1920s and 1930s, the officers who would eventually lead the American armada in its defeat of Japan spent time at the Naval War College participating in and learning from these wargames.2 And the results of the wargames were fed back to the fleet, helping to inform the next Fleet Problem. It was these incessant wargames the prompted Fleet Admiral Chester Nimitz to remark after the war, that “the war with Japan had been enacted in the game rooms at the War College by so many people and in so many different ways that nothing that happened during the war was a surprise—absolutely nothing except the kamikaze tactics toward the end of the war. We had not visualized these.”3

The Marine Corps of the 1930s realized that if it were to remain viable as a service, it needed a mission beyond is role as a constabulary force. Recognizing the need for island bases for the success of the Navy’s plan to defeat Japan, the Marines developed doctrine first to seize and then to defend island bases to allow the fleet to march across the Pacific. Initiated by Major Pete Ellis’ survey of the islands of the South Pacific, the Marines developed the Tentative Manual for Landing Operations (1934) and the Tentative Manual for Defense of Advanced Bases (1936) with the help of dedicated effort by the faculty and staff of Marine Corps Schools. Brigadier General James Breckinridge, Commandant of Marine Corps Schools, “temporarily discontinued Field Officers School classes so that the staff and students could devote their full attention to developing the new doctrine.”

The three efforts discussed above were self-synchronizing, which is to say not synchronized, with no single authority directing their efforts. This led to inefficiency and a lack of common direction. Despite the excellent work occurring in Naval War College wargaming, the college struggled to stay open during the austere, Great Depression-era budgets of the late 1920s and early 1930s. The conclusions reached by fleet commanders and War College staff and students did not always agree, and senior navy commanders in charge of the fleet often did not want to yield to the academics. And despite the apparent utility of seizing island bases to the drive across the Pacific, the U.S. Navy initially invested little in amphibious capability, even when naval construction began anew in 1933.

There were still successes in integrating efforts. Fleet Problem III in 1924 provided the first opportunity to incorporate the Marines into fleet operations and demonstrated that “amphibious operations might have a role to plan in the navy’s sea-control mission.”4 In the mid-1930s, the Fleet Problems began to include a Fleet Landing Exercise (FLEX) component, but often the Marine’s desire to contribute to the sea control mission by seizing islands was superseded by the Navy’s focus on the decisive fleet engagement.5 The opportunity for integration was there, but without a common top-down coordinator, the two branches continued to focus on their independent priorities.

Integrating Today for Tomorrow’s Fight

Today’s Navy-Marine Corps team can learn from these efforts, modeling the commitment to Fleet Problems, Naval War College wargaming, and the single-minded development of amphibious doctrine, but today’s team needs to take it further. The first improvement is to ensure these efforts are integrated. The CNOs FRAGO and the Commandant’s Planning Guidance are a step in the right direction but cannot be the end of integration. An integrated Navy-Marine Corps steering group should be developed to synchronize integration efforts, identifying significant integration development activities, and ensuring alignment among them. A modern version of the Navy General Board as suggested in Joel Howlitt’s 2017 CNO History Award-winning essay could serve this role admirably. The steering group does not need to create additional events but instead would ensure existing events are linked together and align Navy-Marine Corps integration efforts and doctrine where appropriate.

Next, make these three powerful integration mechanisms a priority. Don’t allow LSE 2020 to be a one-off event. Like the Fleet Problems of the interwar years, make the LSEs annual, and make them a defined operational priority for the fleet’s ready naval power, getting as many ships, aviation units, and Marine formations to sea and into the exercise as possible. And for ships unable to sail or other units unable to join, connect them to the exercise via the Navy Continuous Training Environment (NCTE) and after action review mechanisms.

Once complete, consider how the lesson from the exercises will be used. Will they be squirreled away in a lesson learned database, or will they be turned over to these new, powerful brain trusts of the Naval War College and Marine Corps University? Like the interwar period, the Large Scale Exercise and Fleet Exercises should inform, and be informed, by the studies at the two institutions. Give the classified results, all of them, to the war colleges, and let the student and staff pick them apart.

To ensure quality analysis and feedback, the service must send the best officers from all warfighting and combat support communities to the Naval War College and Marine Corps University – not just the officers who happen to be available. There is a saying that if the loss of a liaison officer you sent to another command doesn’t hurt, you’re sending the wrong officer. The same should be true with the Naval War College and Marine Corps University. Accept the tactical risk at the unit level of losing an officer to this effort to buy down the strategic risk of an underprepared officer corps. This is exactly what is called for in the Secretary of the Navy’s Education for Seapower (E4S) Decisions and Immediate Actions memorandum from February of last year. In it, he directed that “All future unrestricted line Flag and General Officers will require strategically-focused, in-residence master’s degrees.” The Navy’s Chief Learning Officer further notes that “the critical months of in-residence study afford each officer a unique chance to read, think reflect, and interact with their future fellow Fleet and Marine Operating Force Commanders…”6

While these future operational commanders are in residence at the War College and Marine Corps University, make it worth their while to attend these prestigious institutions. Rather than sticking to a rigid curriculum designed to satisfy graduate school accreditation and Joint Professional Military Education wickets, give these officers the hard problems to solve. Give them the tools to “study strategy, policy, operational doctrine, and the effects of new technologies for national strategic advantage”7 that comprise the current curriculum, but then give them real-world tasks, at the appropriate classification levels, and let them apply that knowledge. Not just in select groups like Gravely and Halsey, but across the board – putting large numbers of minds against our hardest problems to come up with a range of solutions, just like the interwar period’s Naval War College did.

And while sending the best and brightest to in-residence programs, more integration is needed in each institution. A recent Proceedings article called for higher percentages of Marines at the Naval War College and filling all the Navy billets at Marine Corps University. This is spot on and should be implemented with urgency. If we are going to ask the Naval War College and Marine Corps University to tackle problems of integration, they must have an integrated staff and student body. Then allow wargaming departments, now with a significant pool of frontline operators available to run the games, refight the LSEs and determine were improvements can be made. And finally, feed the output from these wargames into designing the subsequent LSEs, to take advantage of the lessons learned from these multiple interactions.


The tools are in place and a roadmap is available for developing Navy-Marine Corps integration in peacetime. The interwar use of annual Fleet Problems, Naval War College wargaming, and Marine Corps amphibious doctrine development focused the efforts of all three on preparing for war against Japan. Using those same tools and the lessons learned from their shortcomings, Navy-Marine Corps warfighting and warfighters can achieve unprecedented levels of integration and be prepared for the next great Pacific war when it comes.

CAPT Jamie McGrath, USN (ret.), retired from the U.S. Navy after 29 years as a nuclear-trained surface warfare officer. He now serves as a Deputy Commandant of Cadets at Virginia Tech and as an adjunct professor in the U.S. Naval War College’s College of Distance Education. Passionate about using history to inform today, his area of focus is U.S. naval history, 1919 to 1945, with emphasis on the inter-war period. He holds a Bachelor’s in History from Virginia Tech, a Master’s in National Security and Strategic Studies from the U.S. Naval War College, and a Master’s in Military History from Norwich University.


1. Albert A. Nofi, To Train the Fleet for War: The US Navy Fleet Problems, 1923-1940 (Naval War College Press: Newport, RI, 2010), 303-315.

2. John R. Kroger memorandum to Secretary of the Navy, Graduate Strategic Studies for Flag and General Officers, dated 11 December 2019. On 07 December 1941, 83 of 84 active Navy flag officers were graduates of the US Naval War College in residence program at the beginning of World War II.

3. Chester W. Nimitz [FAdm, USN], speech to Naval War College, 10 October, 1960, folder 26, box 31, RG15 Guest Lectures, 1894–1992, Naval Historical Collection, Naval War College, Newport, RI,

4. Craig C. Felker, Testing American Sea Power: US Navy Strategic Exercises, 1923-1940 (Texas A&M University Press: College Station, TX, 2007), 94-97

5. Ibid., 104-109

6. Kroger memorandum.

7. Ibid.

Featured Image: Sailors and Marines of the USS Ronald Reagan stand at attention before manning the rails on the flight deck in Pearl Harbor, Hawaii, June 28, 2010.
U.S. Navy photo by Petty Officer 3rd Class Oliver Cole

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