Army Promotes Nashville District Deputy Commander to Lieutenant Colonel

The U.S. Army promoted Nashville District’s deputy commander, Maj. USACE Todd A. Mainwaring, to the rank of lieutenant colonel Feb. 2, 2024, with Corps of Engineers officials, distinguished visitors, family, friends, and the district’s workforce present to celebrate a career milestone.

Lt. Col. Robert W. Green, Nashville District commander, welcomed guests and recognized Mainwaring’s distinguished service as deputy commander during a promotion ceremony in the Tennessee Room at the Nashville District Headquarters.


Green pointed out that Mainwaring has served in multiple positions and assignments with increasing difficulty and excelled in every one of them. As his deputy in the Nashville District, Green said that he routinely solved problems that he didn’t even know were problems because he identified them and worked with the team to develop a solution. And his forte usually involved coaching and developing others, added the commander.

“One of my mentors told me one time that with promotion to lieutenant colonel, you are truly becoming the executive backbone of the Army,” Green said. “There is an adage that lieutenants run companies, captains run battalions, majors run brigades and divisions, and lieutenant colonels run the Army.”

army promotion pinning
Todd A. Mainwaring’s mother Debbie and son Calvin pin on the new rank of lieutenant colonel during a promotion ceremony Feb. 2, 2024, at the U.S. Army Corps of Engineers Nashville District Headquarters in Nashville, Tennessee. His wife Darcy in the background also assisted with his promotion. Mainwaring is the Nashville District’s deputy commander. USACE PHOTO BY LEE ROBERTS

Green said lieutenant colonels in the Army are doing the tough jobs and they work to solve the tough Army-level enterprise-wide problems.

“I think Todd has proven himself over and over again and is ready for that level of responsibility,” Green stressed.

Retired Lt. Gen. William Grisoli officiated the promotion and administered the oath of office, where the Army’s newest lieutenant colonel solemnly swore to support and defend the Constitution of the United States and to faithfully discharge his duties.

The general said after his own retirement he met and worked with Mainwaring at the United States Military Academy where they served together to shape, mold, and teach cadets.


“I could see over time the pride he has in what he was trying to do, and the drive he has, that he was going to be a unique officer. And I really started to get to know him very well. I ended up teaching with him two-and a-half years. That’s really our connection,” Grisoli said.

The general said to inspire the Army’s future leaders at West Point, it was important to always be prepared to make a difference and ensure the cadets received the instruction they needed to become future Army officers.

“He took it to heart. The one thing I noticed there was his initiative, his good judgment, his common sense, but the other thing I really admired, was he was a caring, humble leader,” Grisoli said. “And that is important. When you get authority and start going up in rank, you really need to be thinking about caring about the folks and being humble there where you are, and making sure they get the mission done”

Grisoli said Mainwaring has proven himself, served with distinction with increased responsibilities, and so the president and secretary of the Army accordingly selected him for promotion and a future command.

“I am really proud of you, and I’m really excited about you going to the next level,” Grisoli told Mainwaring. “And this isn’t his last promotion, I’ll tell you that,” the general said to guests in attendance.

Mainwaring’s wife Darcy, two children, Calvin and Emery, and parents, Retired Lt. Col. John and Debbie Mainwaring, attended the promotion ceremony. Darcy, Debbie and the children assisted in pinning on his new rank insignia. Retired Maj. Gen. Mike Walsh also attended to honor Mainwaring, who previously served as the general’s aide.

Mainwaring thanked Grisoli for his participation in his promotion ceremony, but also for his confidence, mentorship, and for helping to put him on his current career trajectory. He said the general essentially gave him a master’s class in officer ship during his time at West Point.

“A big reason I’m standing here right now… I’m so thankful to have people I can pace my life against,” Mainwaring said. “I think I’ve been able to go further, faster, harder than if we never met.”

In addressing his family, Mainwaring also recognized that his successes are only possible because of his wife, kids, grandparents, parents, siblings, West Point classmates, and extended family loved and supported and strengthened him throughout his Army career. He said his constant has been his wife Darcy and his kids, and he expressed his love and thankfulness to Calvin and Emory, and especially his wife.

Speaking to his wife, he noted his appreciation to her for “the hundred little things that it cost to get here, the cash that I wrote that you had to pay. I’m so grateful that you did.”

Mainwaring’s official date of rank is Feb. 1, 2024. He became the deputy commander July 1, 2022. He assisted Lt. Col. Joseph Sahl, the previous commander, and Green in directing all the water resource activities of the U.S. Army Corps of Engineers throughout the Cumberland River Basin, and navigation and regulatory matters in the Tennessee River Basin, an area of more than 59,000 square miles, with 49 field offices touching seven states and a work force of over 700 federal employees.

Although he grew up an Army brat, Mainwaring calls Dothan, Alabama home. He graduated from the United States Military Academy at West Point, New York, with a Bachelor of Science degree in Civil Engineering where he received his commission in 2007. He holds two Masters of Science degrees in Civil Engineering and Management Science from the United States Military Academy and Stanford University.

From 2010 into 2011, Mainwaring served as aide-de-camp to the U.S. Army Corps of Engineers Mississippi Valley Division commanding general. He then took command of the 643rd Engineer Company, 84th Battalion at Schofield Barracks, Hawaii. During this assignment, he deployed his headquarters to Camp Covington, Guam, where they managed small engineer team simultaneously dispersed across seven countries in the South Pacific where they constructed more than 20 projects.

After command, he attended graduate school at Stanford University to study sustainable construction and energy efficient building design. With this knowledge, he returned to West Point from 2016 to 2019 to teach civil engineering. He then attended the Command and General Staff College and in 2020 joined the 7th Special Forces Group (Airborne) at Eglin Air Force Base, Florida as the group engineer.

He is a graduate of the Engineer Officer Basic Course, Aviation Captains Career Course, and Army Command and General Staff College. He is also a certified Project Management Professional and Professional Engineer.

Mainwaring thanked everyone at the conclusion of the promotion ceremony for attending and noted he still has work to do.

“What we do here matters, and I’m really proud of that,” Mainwaring said to the workforce in the Nashville District. In his future assignment, he said he looks forward to doing his best to achieve and fulfill his responsibilities in meeting challenges.

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