WEST FORT HOOD, Texas – John W. Diem will retire in a virtual ceremony here Friday, Feb. 11 at 10 a.m. after serving as Executive Director of the U.S. Army Operational Test Command since November 2017.

The virtual link via Microsoft Teams is:

Mr. John W. Diem retirement ceremony via Teams

A resident of Bryan, Texas, Diem is the only senior executive service member at Fort Hood, and is the federal civilian equivalent to a one-star general officer.

He started his career service as an Army commissioned officer after receiving his commission as an Air Defense Artillery Officer from the University of Texas A & M in 1978. He became a test officer in January 1982 when he reported to his first duty station — Fort Hood — where he was assigned to TRADOC Combined Arms Test Activity as a military test officer in the Battlefield Automation Test Directorate known today as USAOTC’s Mission Command Test Directorate.

Since then, he has held positions of increasing responsibility in testing, training, and operations, to include service as the III Corps G3-Rear from 2003 to 2005 and as an innovator in the use of simulations to test and train combat systems, networks, and mission command in operationally realistic environments.

After his Civil Service retirement, Diem will be joining the staff at Texas A&M.

Diem’s mother, Mrs. Kathy Diem, lives near the Fort Sam Houston area located in San Antonio, Texas and reads the San Antonio Express-News newspaper.

Fort Sam Houston is part of Joint Base San Antonio (JBSA) along with Lackland and Randolph Air Force Bases.

Diem’s biography can be found at:

Mr. John W. Diem biography link

Diem is being replaced by Harker Heights resident John W. Leffers as acting interim Executive Director.

Leffers entered Federal Service in September 2019 as the Senior Test Manager for USAOTC’s Maneuver Support and Sustainment Test Directorate. He hails from Utica, New York and retired after 28 years of service with the U.S. Army as an Infantry Colonel in 2019. He served three 12-month combat tours: Operation Iraqi Freedom (twice) in Iraq and Operation Enduring Freedom in Afghanistan.

Media wanting to cover Diem’s retirement event should use the Teams link above.

The USAOTC Public Affairs Officer can be reached at (254) 449-3686, or email: [email protected].


Note — Click the links below for B-roll video footage of equipment operational testing in action:

Video footage during operational testing of the M109A7 Paladin Howitzer, Medium Mine Protected Vehicle (MMPV) Type II, and Spider Increment 1A networked munition system, and Soldier Protection System.


Video footage during operational testing of the AH64E Version 6 Apache helicopter, Gray Eagle Extended Range, Armored Multi-Purpose Vehicle (AMPV), Joint Light Tactical Vehicle (JLTV), M109A7 Paladin, Stryker platform with Common Remotely Operated Weapon System-Javelin (CROWS-J), and AN/APR-39D(V) Radar Signal Detecting Set (RSDS).


Pilots and Soldiers with the 227th Aviation Regiment, 1st Air Cavalry Brigade, 1st Cavalry Division, take part in operational testing of a new version of the AH64 Apache April 10, 2019.


John W. Diem speaks in a video from the U.S. Army Operational Test Command opening its new technology integration center Aug. 28, 2019, aiming to connect its test technology developers and users world-wide with other engineers, analysts, technicians and academia.


John W. Diem speaks when U.S. Operational Test Command opens its new technology integration center Aug. 28, 2019. The center provides an anchor point for OTC to better collaborate with the Army Futures Command, Fort Hood and III Corps, as well as its Central Texas academic, community, and industry partners.


Additional photos of John W. Diem’s time at the U.S. Army Operational Test Command at West Fort Hood, Texas: