As Gen. James F. Amos prepares to become commandant of the Marine Corps, some in Washington say the survival of the Marines will be at stake during Amos’ tenure.

Retired Marine Col. John Keenan, editor of Marine Corps Gazette, wrote that possibly no commandant since Gen. Alexander A. Vandegrift of the post-World War II era “has faced such a serious challenge to the Marine Corps.” When some wanted to eliminate or marginalize the Marine Corps during the postwar unification fight in Washington, Vandegrift gave his May 6, 1946 “bended knee” speech arguing for a separate service branch of “Devil Dogs,” the term for Marines created by the Germans at Belleau Wood 1918.

Vandegrift called the Marine Corps “a small, highly skilled body of specialists which has earned world-wide professional prestige without benefit of West Point tradition or General Staff direction. Its success rests squarely on its development of a form of military service based on the premise that while the American man in uniform is a warlike individual, he does not respond to methods applicable to the conscript armies of central Europe. The Marine Corps’ guiding principles stem from such intangibles as democracy, recognition of the individual and the timeless value of personal leadership as opposed to machine direction.” The bottom-line justification, then and now, for the Marine Corps was rapid insertion of light forces via amphibious and – today – aerial assault.

Defense Secretary Robert Gates selected and Barack Obama nominated the courtly, patrician Amos in preference to blunt-spoken Gen. James N. Mattis – a choice seen at the time as a snub of Mattis, who exudes machismo and is fully as blunt-spoken as current commandant Gen. James T. Conway, but who also cites lessons from classic literature and quotes poetry. Gates has ordered a major review of the Marines’ mission. Critics say Gates is ready to challenge the need for amphibious-assault capability and – in an era of tightfisted budgeting – the existence of the Marine Corps itself. “In the 21st century, what kind of amphibious capability do we really need to deal with the most likely scenarios, and then how much?” Gates asked rhetorically in a speech last May.

On Amos’ watch, Marine leaders must show progress with controversial programs like the Expeditionary Fighting Vehicle (EFV) and the F-35B Lightning II Joint Strike Fighter (JSF). Gates wants to cancel or cut back on EFV, a 68,000-pound amphibious assault vehicle capable of 25-30 knots at sea and 45 miles per hour on land, but with a history of technical issues and cost overruns. An Aug. 24, 2010, demonstration for the press at Oceanside, Calif., in which a revised, improved SDD-2 prototype of the armored, aluminum-hulled EFV performed without any flaw, may have helped the program. Said Conway: “There are programs that are absolutely and vitally important. One of those is our EFV.”

But is Amos, 63, the right choice to replace Conway, also 63, as the top leatherneck in troubled times? He is the first naval aviator to lead the Marines. Using the callsign “Tamer” (as in “lion tamer”) Amos logged thousands of hours in the cockpits of F-4 Phantom IIs and F/A-18C/D Hornets and has more experience flying from aircraft carrier decks than most Marines. In 2003, as a major general, Amos commanded the 3rd Marine Aircraft Wing in the U.S.-led invasion of Iraq. More importantly, Amos is comfortable on Capitol Hill and among industry CEOs. An officer who worked with him said Amos is soft-spoken but persuasive.

As for Mattis, 56, he is a seasoned war veteran who in 2003 led leathernecks on the longest sustained march in Marine Corps history, and during the bloody battle of Fallujah, Iraq, in 2004. While Mattis seemed to brand himself as the archetypal macho Marine in a 2005 speech when he said of Taliban militants, “it’s a hell of a lot of fun to shoot them,” he is also nicknamed the “Warrior Monk” because of his reputation as a scholar. Mattis was commander of Norfolk, Va.-based U.S. Joint Forces Command, which Gates wants to dissolve as part of an effort to spend Pentagon dollars more efficiently. Far from denying another job to Mattis, who is affectionately called “Mad Dog” by some Marines, Gates followed up the Amos appointment days later by announcing the nomination of Mattis to be head of U. S. Central Command (CENTCOM), headquartered at MacDill Air Force Base, Fla., and responsible for operations in the Middle East and Asia. Mattis replaced, and nominally supervises, Army Gen. David H. Petraeus, now the U.S. and NATO commander in Afghanistan. Given Petraeus’s clout in Washington, Mattis is expected to give the Army general a fairly free hand while focusing his attention on Iraq, Somalia, Yemen and other hot spots.

Lt. Gen. Joseph F. Dunford Jr., an infantry officer, is expected to replace Amos as assistant commandant.

Amos and Dunford await Senate confirmation, which is expected to come without difficulty. The Senate confirmed Mattis speedily and he is now on the job at CENTCOM.