The military is taking Macgregor’s challenge seriously, in part because the retired colonel has spurred interest in his reform ideas from one of the most important players in the defense community, Senate Armed Services Committee Chairman John McCain. McCain was said to be impressed after Macgregor and Admiral Mark Fitzgerald briefed him on the new force design last January 17, telling his staff to set up briefings for Macgregor with other senators. Then, in September, after Macgregor’s simulations were completed, he briefed senior Senate Armed Services staffers, arguing that replacing BCTs with RSGs would make Army formations more lethal and eliminate the budget redundancies in the current system, with potential savings of tens of billions of dollars.

“Macgregor scares the hell out of the Army,” says a senior Joint Chiefs war planner. “What he has proposed is nothing less than the dismantling of the Big Green Machine, getting the Army to embrace a future of lighter, more agile forces than the big lumbering behemoth which takes forever to spool up and deploy. I’ll bet the armor and airborne guys are furious. Reform my ass: Macgregor has walked into the zoo and slapped the gorilla.”

Indeed, one of the pitfalls of Macgregor’s Army career was that he slapped a few too many gorillas along the way. He has long been known for his ability to alienate senior officers, not least because he suggested they spent their time sucking up to their superiors, instead of figuring out how to wage war.

In January of 2001, Defense Secretary Donald Rumsfeld insisted that U.S. Central Command General Tommy Franks and his Iraq war planning staff meet with Macgregor, who argued that the U.S. should scale back its Iraq fighting force, racing to Baghdad with a mobile blitz using just 50,000 troops. Franks, and senior Army leaders, rejected Macgregor’s advice, resented his intervention (one commander walked out of the room in disgust, while Macgregor was talking) and after the end of the war, sidelined him in a series of meaningless staff jobs. After being passed over for promotion, Macgregor retired in 2004. Despite this, he retains his outsized influence in Army circles, where his ideas are circulated–and quietly supported. “Doug Macgregor is a pain in the ass,” retired Brigadier General Mark Kimmitt notes, “but that doesn’t make him wrong. Serious people take him seriously.”

In his campaign for reform, Macgregor has recruited a number of high-profile retired military officers to what is known in the military as “the Macgregor Transformation Model.” Macgregor and his supporters presented his model to a packed house on Capitol Hill in November of 2013 and the next year, in these pages, he compared the Army to a nine passenger rowboat–where “four would steer, three would call cadence and two would man the oars.”[1]

Who is right in the great debate? Macgregor was reluctant to provide detailed, proprietary information on how his warfighting scenarios were actually designed, but he agreed to allow me to talk to one of his key simulators, who confirmed that Macgregor’s team comprised officers from every service, who spent months designing the simulation and reviewing the data. “The design of the RSG took eight years,” this former senior military commander told me, “but the actual simulation, based on highly complex mathematical models that are used by the military, started in June and ran for seven weeks. Getting the data right was hell on earth. What we did had to be empirical, provable, convincing.”

Some skeptics suggest that the Macgregor-McMaster debate is less about the Army’s structure than its budget, which has been pared down by sequestration and is therefore being more fiercely fought over. “The Russians have made improvements in their military, but in my opinion the Army exaggerates their capabilities. Hell, they can’t even get their draftees to show up,” says David Majumdar, a defense analyst and Russian military expert at the Center for the National Interest. “The bottom line here is that increasing the Russian threat is a good strategy to increase the Army budget. This isn’t about fighting the Russians, this is about fighting the Congress. This is about getting past sequestration.”

Retired Army Colonel David Johnson, a regular adviser to the military at the Rand Corp., disputes this and says the debate on Army capabilities is as much about weapons as anything else. “We might or might not be fighting the Russians,” he says, “but we’re almost certainly going to be fighting Russian weapons.” On the day that I spoke with him about the Macgregor-McMaster debate, in mid-September, Johnson had just returned from briefing McMaster and his team about the issue, concluding that the U.S. has “important capability gaps” that “put our ground forces and future strategies at high risk.” For Johnson, “fighting their weapons” means countering not just military formations, but sophisticated air defenses, ballistic missiles, and special operations forces”–things the Russians are good at. “It’s a new battlefield,” he concludes, “in which nothing survives that flies under 25,000 feet.”

McMaster also says the debate “has nothing to do with trying to break sequestration,” Instead, he told me during a wide ranging telephone interview, “it has to do with carrying out the mission that we have. … The real question here is not about the budget, it’s about the strength and capabilities of our forces. We have to be prepared for every contingency.” And that includes fighting on for far longer than Macgregor thinks might be necessary, as happened in Iraq and Afghanistan. For McMaster, the current Army structure is the best way to do that. “We’re not going to abandon the Brigade Combat Team,” he says. “It’s a building block and it’s a good one. It works.”