Sean Mullen was Delaware's third casualty in Afghanistan campaign.

Boyhood companions and high school classmates of Warrant Officer Sean W. Mullen are remembering the fallen U.S. Army soldier as a friend with a kind soul, ready smile and adventurous spirit.

Mullen, 39, died Sunday, June 2, 2013, in Ghur Ghuri, Afghanistan, of injuries he suffered from the explosion of an improvised bomb. He was on his sixth overseas deployment.

Mullen spent his formative years in Dover, where he played Camden-Wyoming Little League baseball, was a member of Boy Scout Troop 24 and attended Caesar Rodney High School, graduating in 1992. He also attended Delaware Technical and Community College, where he majored in criminal justice.

Fellow CR alumnus Rick Stewart recalls going on "amazing" camping expeditions with Mullen to Voshell's Pond, Camp Rodney, and, in particular, a memorable canoeing trip to Canada.

The Scouts made the excursion via bus and a single-engine sea plane that took them to a remote backwoods area, Stewart said.

"We camped, fished, and had fun," he said. "I think we canoed roughly 75 miles and portaged our equipment and canoes over land."

Mullen also pitched in Little League, where he would play mind games with the opposing teams. In a typical inning, he'd allow a batter to settle in, and then get ready to pitch. Then he'd wait … and wait … and wait … before throwing the ball. Other times, he'd toss the ball immediately. This tactic was designed to keep the offense off kilter – and it worked.

"It would drive me and the other batters nuts," Stewart said.

Mullen's parents, William and Miriam, still live in the Crossgates area, where Mullen spent time with a regular group of neighborhood kids.

"I'll always remember him with a silly giggle as one of the Crossgates/Mayfair/Rodney Village crew," said classmate Valerie Jones. "I remember him fondly as a great friend and a kind, treasured man."

"I have the fondest memories of Sean," said 1992 graduate Michele Robinette. "He was one of the kindest people I know and always had a smile on his face. I am proud to have known him."

"Sean was the nicest and most kind person ever," said Lanie Bailey Thomas, also a fellow classmate.

Mullen was assigned to an airborne Special Forces Detachment at Fort Campbell, Ky., deployed to Afghanistan.

He enlisted in the Army in November 1995 as an infantryman, but volunteered for Special Forces training. He rose through the ranks as an enlisted soldier and had been deployed several times to Iraq and Saudi Arabia.

He was accepted into the warrant officer corps in November 2012.

Gov. Jack Markell ordered United States and Delaware flags be flown at half-staff in Mullen's honor until Friday, June 7.

"Our hearts break for his family and, on behalf of our state, we offer them our deepest gratitude and sympathy," Markell said.