Col. Albertus W. Catlin stood on a rise in the ground with his field glasses and watched his Marines advance through the waist-high wheat toward the woods 400 yards away.

He was closer to the fighting than he should have been and would soon pay the price. But he was a big, cigar-smoking Marine who had been serving aboard the USS Maine when it blew up in Havana harbor in 1898, and he had a Medal of Honor from the fighting at Vera Cruz in 1914.

This was June 6, 1918, though, and as his men walked toward the old French hunting preserve of Belleau Wood, they were about to launch a bloody new era in the history of the Corps.

This June marks the 100th anniversary of the largely forgotten World War I Battle of Belleau Wood in northern France. Marines are remembering the landmark, three-week fight with events at home and overseas.

The National Museum of the Marine Corps, in Triangle, Va., is unveiling an exhibit of World War I art on June 6.

In April, French President Emmanuel Macron gave the White House an oak sapling from Belleau Wood, where, he said, “the blood [of Americans] was spilled to defend France.”

The battle was a modest affair compared with the titanic World War I struggles that went on for months. But, fought across open fields and in the dark, overgrown woods, it seemed especially grim, with hand-to-hand fighting, fixed bayonets and poison gas attacks.

One Marine, Fred W. Stockham, was awarded the Medal of Honor posthumously for giving his gas mask to a wounded comrade whose mask had been shot off. Stockham then died of gas poisoning.

“It has been a living hell,” Lt. Clifton B. Cates, 24, a future Marine Corps commandant, wrote his mother. “We were shelled all night with shrapnel and gas shells. … It was mustard gas and a lot of the men were burned.”

It was a battle that changed the Corps. “For all intents and purposes, the old warriors of the U.S. Marine Corps were virtually wiped out,” wrote historian George B. Clark.

As they attacked, the Marines “left behind fourteen decades of small-scale skirmishes with insurgents [and] pirates … and entered the industrialized world of massive fire power and wholesale slaughter,” historians Edwin Howard Simmons and Joseph H. Alexander have written.

At Belleau Wood, they went up against a professional German army equipped with machine guns and heavy artillery, at the flood tide of a breakthrough near Paris that seemed about to end the war.

The Marines’ opening assault through the fields, at a walk, began like a scene from the Civil War a half century before. (One regiment still had 332 mules in France to haul supplies.)

But the fighting would soon degenerate into a free-for-all in the tangled forest that forecast similar combat in the Pacific jungles of World War II.

“The frowning wood, with its splintered trunks and shell-shattered branches [and] the jungle of undergrowth at the edge [was] filled with threat and menace,” Catlin wrote in a 1919 memoir. It was also filled with 1,000 or more German defenders.

The assault began at 5 p.m.

“My hands were clenched … as I watched,” Catlin, then 49, wrote. He was confident the men in the initial push, about 1,000 in two battalions, wouldn’t fail. “They might be wiped out … but they would never break.”

An ‘almost impossible’ task

By June, 1918, Russia had taken itself out of the war against Germany and Austria-Hungary. Germany had shifted thousands of soldiers from Russia to France and launched a massive spring offensive to end the war.

But the German attack was running out of steam in the face of stiffening allied resistance and the arrival of thousands of American soldiers and Marines.

At Belleau Wood, where the Germans had paused, the brigade of Marines, with elements of the Army, was ordered to counterattack.

The Marines made a colorful group: Men who had come to France from skirmishes in Haiti and Cuba; officers such as Maj. John “Johnny the Hard” Hughes, who had once suffered a compound leg fracture and set it himself, and enlisted men like British-born Henry L. Hulbert, who would be killed in action four months later at age 51.

There was a track star from Yale, John W. Overton, who had set a world indoor record for the mile and would be killed in action a month later; an Irish immigrant gunner named James Gallivan, who would be wounded in the leg and earn many medals, and a 25-year-old lieutenant and sketch artist, John W. Thomason Jr., who would record what he saw with pencil, pen and paper.

As Col. Catlin watched the attack unfold that evening he was aware that most of the Marines didn’t know “the almost impossible task that lay before them.

“I knew,” he wrote, “and the knowledge left me little comfort.”

Part of the attack faltered almost immediately.

Maj. Benjamin S. Berry’s battalion, which had to cross almost a quarter mile of open ground under intense enemy fire, was cut down and stopped at the edge of the woods.

A 44-year-old Marine sergeant, Dan Daly, who already had two Medals of Honor from earlier conflicts, is said to have yelled to the men, “Come on, you sons of bitches, do you want to live forever?”

But the enemy fire “was more than flesh and blood could stand,” Catlin remembered. The Marines hit the dirt, waited until dark, and pulled back.

Berry, the son of a prominent Pennsylvania politician, was seriously wounded in the left arm. Catlin was shot in the chest by a sniper. The bullet went through his right lung — “in at the front and out at the back,” he recalled.

“It felt exactly as though someone had struck me heavily with a sledge,” he wrote. “It swung me clear around and toppled me over on the ground. When I tried to get up, I found that my right side was paralyzed.”

He was taken to the rear and out of the action. (Catlin survived, but retired in 1919 and died in 1933 after a years of ill health resulting from his war wound, according to his newspaper obituary.)

The battle went on without him.

Sketches of a ‘World at War’

The enemy soldier wears a plain enlisted man’s cap with a scarlet band around the bottom. He is a red-faced man with a light mustache and a dignified look. His portrait, in pencil and tempera on paper, is called, “Head … German Soldier 3.”

But there are bullet holes in the drawing that Marine officer John W. Thomason Jr. sketched — holes made by Thomason’s .45-caliber pistol.

The drawing is one of several Thomason sketches displayed, among many other works, in the museum’s exhibit, “A World at War: The Marine Corps and the U.S. Navy in World War I.”

Two other Thomason portraits of German soldiers also were pierced by bullets from his .45, apparently during target practice, the museum said.

Thomason, a former newspaper reporter and illustrator, drew striking scenes of his comrades and the enemy, often with just pen or pencil, sometimes on paper scrounged from abandoned German bunkers.

One unfinished piece, titled “Before Zero Hour,” shows grim-looking Marines in overcoats standing the bluish light of a trench waiting for the signal to attack. One man seems to flinch as the yellow hues of dawn break in the background.

About 4,000 casualties, about 1,000 killed

Although Berry’s attack failed, a simultaneous assault on another part of the woods by Maj. Berton W. Sibley’s battalion fared better.

“The minute they got into the woods our boys found themselves in a perfect hornets’ nest of … gunners, grenadiers and riflemen,” Catlin recounted. “There were machine gun nests everywhere — on every hillock … every ravine … and every gun was trained on the … Marines.”

As more and more Americans poured into the woods, some found the Germans faint of heart.

“They are yellow … and will not fight like men,” Pvt. Edward Cary wrote home to St. Louis, according to Catlin’s account. “I could lick a squad of them with a soup ladle.”

But they counterattacked the Marines nine times between June 6 and June 15.

By June 26 all of the Germans had been driven from Belleau Wood.

On June 30, the grateful Sixth French Army issued an order renaming Belleau Wood “Bois de la Brigade de Marine.”

To earn the honor, the Marines had taken about 4,000 casualties, including about 1,000 killed, said Annette Amerman, a branch head and historian with the Marine Corps History Division.

That was about 55 percent of the brigade’s original strength, according to historians Simmons and Alexander.

It was, they have written, the largest number of casualties suffered by a single American brigade during the war.