Trench warfare tips: What US troops need to know from Ukraine

U.S. Army veteran Ryan O’Leary, has spent so much time assaulting Russian trenches in Ukraine that he’s made it his handle on Twitter, now X: @IhateTrenches.

“Your CQB [close-quarters battle] is violent, but nothing compares to trench warfare,” O’Leary told Task & Purpose. “Most of the enemy we’re fighting at like five meters or less distance. The only way you can get everyone out of the trench is by going into the trench.”

O’Leary leads foreign volunteers in “Chosen Company,” which is attached to Ukraine’s 59th Motorized Brigade. Although the unit has shown it is good at clearing enemy trenches, it is a miserable experience to defend trenches, especially during Ukraine’s cold winters, he explained

During the past 11 months, members of the company have used their military training to adapt to the conditions on the ground in Ukraine, O’Leary said. Task & Purpose spoke and texted with O’Leary, who is still in Ukraine, via the Signal app. Mastering the art of trench warfare requires getting your reps in, he said.

“You have to practice it a lot, get good at it,” O’Leary said. “Otherwise, you’re going to die really quick.”

The lessons that O’Leary has learned about trench warfare could help American service members if they are ever called upon to fight against an adversary with extensive trench lines and other fixed defensive positions.

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A key lesson has been that trench warfare is much more difficult than the type of close-quarters battle that U.S. troops have engaged in over the past 20 years, he said.

In close-quarters battle, U.S. troops can fire a rocket into a building to kill the people inside, O’Leary told Task & Purpose. Trenches are very difficult to demolish. Artillery strikes must land directly inside the trenches to be effective, and that does not happen often.

It’s also much easier for enemy forces to hide in trenches, which have a lot of fortifications that need to be overcome, he said. With CQB, the attacking force can isolate a building or city block. That is not possible when assaulting enemy trenches, which have numerous shooting positions to envelop an attacking force.

“So, it’s more of utilizing small unit tactics and smaller movements to break the lines of areas,” O’Leary said. “Once you break a line, that’s when you can really push.”

When O’Leary joined the Army in 2004, he learned the basics about digging a shooting position and clearing a trench or bunker, but trench warfare has evolved since then with the advent of commercially available drones, as the Russian invasion of Ukraine has shown, he said.

“There’s always eyes in the sky,” O’Leary said. “Someone is always seeing stuff.”

The Russians have also used drones to drop grenades into Ukrainian trenches, underscoring why it’s important for troops who fight in trenches to use camouflage netting and other means of concealment to avoid being detected and targeted, he said.

“Your routine in the trenches has to be done differently,” O’Leary said. “You can’t just have people sitting up, watching the front lines. They’ll just get hit. If you sit in an uncovered position — or even a covered position that they’ve seen you walk into — you’re just going to get smashed.”

However, the methods of keeping Ukrainian troops undetected by drones vary depending on where they are on the front line because Russians use different types of drones in different sectors, O’Leary said.

“There’s no one singular fix to protecting yourself from drones,” O’Leary said. “You’ve basically got to learn on the fly.”

Since most of the drones being used in Ukraine are made in China, the Chinese military is likely learning lessons for future wars based on which of the unmanned aircraft being used by the Russians are most effective, O’Leary said.

Retired Army Lt. Gen. Ben Hodges, former commander of U.S. Army Europe, also emphasized that a major component of modern-day trench warfare is avoiding being detected by enemy drones.

“A combination of concealment from visual detection and thermal imaging is important for surviving in these trenches,” Hodges told Task & Purpose.  

Hodges noted that he has been struck by how much garbage and discarded equipment are typically seen in or near Russian trenches, indicating that the Russian troops are not disciplined, nor are they prepared for fighting.

Hodges also said the U.S. has stockpiles of many of the weapons that appear to be most effective in trench fighting, including drones, artillery, hand grenades, and small arms 

But he also sees areas the Russians have developed in which the U.S. would need to improve or develop new weapons or tactics if U.S. troops were to ever find themselves opposed to Russian forces.

“The Russians have done a good job protecting their trenches with minefields,” Hodges said. “We’ll have to deal with them as well one day. They’ve also invested enormously in artillery to support their trenches. So that means an effective counter-fire effort will be necessary to suppress the Russian trenches and their supporting artillery to enable our own assaults to get into the trenches to clear them.”

Learning trench warfare

Even though the United States has provided Ukraine with nearly $45 billion in military assistance since February 2022 — including M1 Abrams tanks and High Mobility Artillery Rocket Systems, or HIMARS — the conflict has bogged down into trench warfare.

With Ukraine and Russia essentially evenly matched technologically, neither side has been able to make much progress in recent offensives, said George Barros, a Russia analyst and Geospatial Intelligence Team Lead with the Study of War think tank in Washington, D.C.

The Russians have supersaturated the front lines with land mines, and Ukraine has found it needs more tanks, infantry fighting vehicles, tactical air defense systems, and other weapons from the West to breach Russia’s defenses, Barros told Task & Purpose.

And given the pre-modern conditions, many experts wonder if the U.S. would fare any better in a similar conflict.

U.S. service members already receive some training on trench warfare. For example, soldiers train to attack trenches and bunkers protected by land mines, wire, and other obstacles as part of their rotations to the National Training Center at Fort Irwin, California, said Army Brig. Gen. Curtis D. Taylor, commander of the training center.

“To successfully breach these obstacles, units must employ the full combined arms team to set conditions, obscure the enemy, and reduce the obstacle while under direct and indirect fire,” Taylor told Task & Purpose

Army units also train how to pause offensive operations to defend trenches and other survivability positions, Taylor said.

“While units are defending, the opposing force will almost always attack with a combination of artillery and enemy drone swarms in order to set the conditions for ground maneuver,” Taylor said. “This forces rotational units to disperse, to dig in, and to be constantly vigilant of enemy attacks from the air.”

A lot of the training that soldiers receive at the National Training Center involves helping them understand how they can be detected visually or on the electronic warfare of thermal spectrums, Taylor said. Soldiers must train how to conceal themselves from the opposing force, which has drones as well as electronic definition and thermal imaging capabilities.

Marines are also trained on how to conduct defensive operations, which can include having engineers dig trenches, said Maj. Joshua Pena, a spokesman for Marine Corps Training and Education Command.

“However, it is just one of the many options of a list that is non-exhaustive,” Pena told Task & Purpose. “The emphasis is on the commander’s ability to employ a variety of defense tactics dependent on the operational situation.” 

When asked if the Marines had updated their training based on lessons from Ukraine, Pena said that the Marine Corps Center for Lessons Learned, or MCCLL, regularly writes reports on global events that the Corps uses as part of ongoing changes to its force structure design and other initiatives.

“Training and Education Command will continue to use the MCCLL platform to inform decisions surrounding Marine Corps operations, training, and doctrine, as required,” Pena said.

Still, it would take the U.S. military a long time to match the Ukrainian military’s level of understanding of how trench warfare works on a modern battlefield, O’Leary said.

“If for some odd reason, the U.S. ever had to go into trench warfare, it would be an extremely costly month or two before they really figured things out and started adjusting,” O’Leary said. “Unless you have actually been here and done it and seen it a bunch, you’re not really going to get a grasp on exactly how it is.”

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