Britain's Royal Marines were 'victorious' in a mock desert battle with US Marines. Here's how the 2 forces stack up

• Britain's Royal Marines got some unexpect attention this fall after reports they had "defeated" US Marines in an exercise.

In October, an exercise in the California desert involving marine forces from across NATO spurred some unintended drama when reports surfaced about the swift defeat of US Marines at the hands of their British counterparts.

Exercise Green Dagger is an annual large-scale force-on-force training event that seeks to prepare US Marine Corps units for upcoming deployments to combat zones or volatile regions.

Marines from the US, UK, Canada, the Netherlands, and the United Arab Emirates "fought" against one another in mock combat drills. During one five-day event, the Royal Marines Commandos defeated their American counterparts despite having smaller numbers.

While many have disputed those reports, they have highlighted the skills and capabilities of both forces. Here's how they stack up.

Royal Marines Commandos

The Royal Marines Commandos are a very interesting unit when it comes to classification. For centuries they served as naval infantry, sailing on Royal Navy ships and fighting on sea and land, in addition to being the troops responsible for enforcing discipline on the British navy.

After the Napoleonic Wars and the British navy's rise to dominance of the seas, the Royal Marines increasingly deployed on land as a naval infantry force. By World War I, they were fighting in the trenches alongside regular infantry units.

It was during World War II that the Royal Marines first entered the special-operations realm. After Germany swept across Europe, the British stood up commando units to take the fight to the continent and keep the Germans on edge.

Initially, the "Commandos," as the units themselves were called, were composed of British Army soldiers and volunteers from many countries that had surrendered to the Nazis.

In 1942, the Royal Marines created their own commando units and added the coveted "Commando" designation to their title. They specialized in amphibious operations against Axis forces in occupied Europe and the Pacific theater throughout the war.

The Royal Marines Commando were the only "Commando" unit of the roughly 40 that existed during the war to survive the major demobilization that came after Germany and Japan surrendered.

Similar but different

While the US and British forces are similar as marines, comparing them is like comparing apples to oranges.

Whereas the US Marine Corps is a combined warfare force that can conduct expeditionary campaigns, the Royal Marines Commandos are a much smaller, more specialized unit that has served as a quick-reaction force of sorts for the UK.

The US Marine Corps has about 200,000 troops and more than 1,000 fighter jets and helicopters and until recently operated its own tank fleet. In contrast, the Royal Marines Commandos field less than 8,000 troops total, only half of them being line infantry. The British Marines have no armor or fighter jets of their own.

Indeed, in terms of capabilities, training, selection, and mission, it would be more fair to compare the Royal Marines with the special-operations units of the US Marine Corps — the Marine Raiders, Recon Marines, and Force Recon Marines.

Even with differences in size and capabilities, both forces have illustrious combat histories.

The US Marines have distinguished themselves in several wars.

Some of their most well-known actions are the Battle of Belleau Wood during World War I, the battles of the Pacific campaign that led the Allies to Japan's doorstep during World War II, the Battle of Chosin Reservoir during the Korean War, and Second Battle of Fallujah during the Iraq war.

The Royal Marines Commandos earned respect and accolades for their actions in several engagements during World War II, but perhaps their most important campaign was during the Falkland War, when they marched across the rugged South Atlantic islands with full combat load — each troop carrying more than 100 pounds of gear — and defeated the Argentines in a series of brutal engagements.

The Royal Marines Commandos are now entering a new phase as British special-operations forces evolve for a world in which potential near-peer warfare against Russia or China has replaced large-scale counterterrorism operations as the main concern.

As part of that modernization, the Commandos are getting new weapons and gear in addition to restructuring into smaller, more agile units.

"We've always been an elite force, but not many people outside the UK know about us. Our military is small compared to the Americans, and the Royals [Marines Commandos] are even a smaller part of that. But we're the fellas you want in a trench when the going gets tough," a former Special Boat Service operator told Insider.

The SBS was for decades the tier 1 special-missions unit of the Royal Marines, recruiting solely from the commandos. It was equivalent to the US Naval Special Warfare Development Group, which used to be called SEAL Team Six.

Nowadays, however, the SBS and the Special Air Service (SAS), its Army counterpart, recruit from the wider British military. And like the Royal Marines, the SBS has always worked closely with their American counterparts.

"We have a close working relationship with the Americans, and we have frequent exchange programs, or at least we had back in my days," the former SBS frogman said. "How that works is usually one of our lads or an American getting seconded to the opposite number for a year or two and serves as a regular member of that team. They train, work, and deploy with them as part of the unit."

Stavros Atlamazoglou is a defense journalist specializing in special operations, a Hellenic Army veteran (national service with the 575th Marine Battalion and Army HQ), and a Johns Hopkins University graduate.