For years after Col. William O. Darby was killed in World War II, fellow soldiers would make a pilgrimage to his family's home just to talk to his mother about the fallen hero credited with forming the U.S. Army Rangers.

Current and former American soldiers will carry on their respect and admiration for Darby this week with a 40-mile march that will end in the northern Italian village where he was killed by enemy fire on April 30, 1945.

More than 60 veterans are expected to participate in Thursday's 70th anniversary event that also will honor 25 soldiers in the 10th Mountain Division who died nearby on the same day Darby was killed.

"All Rangers know that Col. Darby was actually a Ranger forefather and creator of today's Army Rangers," said retired Army Sgt. 1st Class Rick Tscherne, 61, a former Ranger who began the tribute march five years ago after realizing his retirement home in Bordolino, Italy, is not far from where Darby died.

A single German artillery shell killed the 34-year-old Arkansas native and another American soldier in Torbole, at the northern end of Lake Garda.

Darby, a graduate of the U.S. Military Academy, organized and commanded the first American Ranger units formed in World War II. The 1st Ranger Battalion was trained in Scotland by British commandos. Two other battalions later joined them, and together they were known as Darby's Rangers. Darby led them into battles across North Africa, Sicily and Italy, then did a stint at the Pentagon before returning to Europe as the fighting there wound down in 1945.

Darby had been assistant commander of the 10th Mountain for barely a week when he was killed. Hours later, 25 of his soldiers drowned when their amphibious vehicle sank during a nighttime crossing of the lake.

One solider survived the sinking. The bodies of the other 25 were never recovered, and all are still listed by the Pentagon as missing in action.

Tscherne, a native of New York City, decided in April 2010 to hike along the length of Lake Garda's eastern shore to honor Darby, ending in the place where he was killed. Dubbing it the Darby Ranger Challenge, Tscherne completed the march alone the next two years. He convinced an old Army buddy to join him in 2013, and last year he was accompanied by Ben Appleby, a 36-year-old British expatriate and WWII buff who teaches school near Torbole.

This week, Tscherne and Appleby will have plenty of company. About 65 people are expected to join them, including former Rangers and other American military retirees, along with contingents of U.S. paratroopers and airmen based in northern Italy. No WWII Rangers are making the rugged trek, Tscherne said.

Darby Watkins, Darby's 60-year-old nephew, called the march a "phenomenal" way to honor his uncle's memory and sacrifice, something he says he was immersed in while growing up in Arkansas and Mississippi.

Watkins' mother was the colonel's sister, and the siblings' mother lived with Watkins' family for a time. For years after the war, the colonel's former comrades sought out Nell Darby to tell her how much they admired her son.

"I would sit in the corner and kind of hide behind the arm of a sofa and listen to them talk about Col. Darby," said Watkins, a 60-year-old retail manager living in Mobile, Alabama. "They were so devoted to him."

William Darby, who was posthumously promoted to brigadier general, is buried in his Arkansas hometown at Fort Smith National Cemetery.