(CNN) -- Army Maj. Gen. Harold Greene worked his way up the military over 34 years to become a training leader and infrastructure expert in the U.S. effort to heal war-torn Afghanistan, where he was killed Tuesday.
His service took him all over the world, and along the way, he earned two master's degrees in engineering and even a doctorate.
Greene was slain when a gunman believed to be an Afghan soldier opened fire at a training facility in Kabul, hitting the general and several others.
Army Chief of Staff Gen. Ray Odierno described Greene and soldiers who were wounded in Tuesday's attack as "professionals, committed to the mission" in Afghanistan.
"It is their service and sacrifice that define us as an Army," Odierno said in statement.
Greene was the deputy commander of the Combined Security Transition Command, which is responsible for helping transfer security control in Afghanistan to the Afghans.
Pentagon spokesman Rear Adm. John Kirby said the general was a logistics and infrastructure expert helping to lead training efforts.
Throughout his military career, Greene's focus was using technology to make soldiers' lives better, retired Maj. Gen. Robert Scales told The Army TImes.
"He had a real sense of what was important," Scales said. "Harry was always the one who always understood the tactical needs of the close-combat soldiers."
And Greene was someone who many admired, he said.
"He was just very level, down-to-earth," Scales told The Army Times. "It's just devastating that you've got this great genius with this incredible reputation and education, and some Islamist wacko comes in and fires a 10-cent bullet and Harry's life is over. There's a certain unfairness in life that war brings."
'Singular ability to display wisdom'
A native of upstate New York, Greene received his commission as an engineer officer after graduating from Rensselaer Polytechnic Institute in 1980, the Army said. He later earned a master's degree in engineering from that school and another master's in engineering from the University of Southern California.
He also earned a Ph.D. in materials science from USC.
After 1980, he traveled widely and served in posts around the country and the world: Fort Leonard Wood, Missouri; Fort Monmouth, New Jersey; Army Aviation and Troop Command in St. Louis, Missouri; Fort Polk, Louisiana; Germany; Athens, Greece; and Istanbul, Turkey.
Greene had served as deputy for acquisition and systems management in the Army's headquarters in Washington before deploying to Afghanistan, according to an Army website.
His prior assignment was the program executive officer leading the group responsible for "research, development, acquisition, and life cycle management of the Army intelligence, electronic warfare and sensor systems."
When he was promoted to brigadier general in 2009, Greene earned praise for what one military leader called his "singular ability to display wisdom."
"He has the rare abilities to make others better, and that's something very special too because at the level he's at right now his ability to inspire others, to show others the way, is so important as well," Lt. Gen. Stephen M. Speakes said at the time.
Greene told people at the ceremony that his success was part of a team effort.
'Get great things done'
"All I did was try to pull people in the right direction, and they went and did great things. So the reason I'm up here is not what I did, but what all of you did. I know it was truly you guys and gals that did the work the Army recognized today, and for that I thank you," he said.
"I was very lucky. I worked with tremendous people, and over the years I was honored to have jobs where I could work with great people and we could get great things done."
In 2011, Greene gave a farewell speech at the Natick Soldier Systems Center in Massachusetts, where he was the senior commander.
"We've accomplished a lot, but there is still a lot of work to do," Greene said, according to a description of his remarks on the Army's website.
He told the audience he wished he could have made more improvements, like replacing windows so more light would come in.
"The one thing I didn't get to: quality of life and facilities," Greene said. "I wish I could have stayed longer to continue to do more. The workforce here deserves better. We need to keep working to improve the quality of life for the workforce and the soldiers that are stationed here."
CNN's Barbara Starr contributed to this report.