Maj. Gen. Joseph Martin will assume command of the 1st Infantry Division, headquartered at Fort Riley, Kansas, according to Army spokeswoman Cynthia O. Smith.
Grigsby was relieved of command due to loss of confidence in his ability to lead, according to Army spokesman Col. Patrick R. Seiber. Grigsby had been suspended on Friday, but senior Army officials took the additional step of firing him Monday, as more information was gathered.
In an unusual step, Army officials have declined to disclose the nature of the investigation or provide information on what type of incident or violation it involves.
One senior Army official said Monday the matter is being investigated by the service and does not involve other law enforcement agencies. The official was not authorized to discuss the case publicly, so spoke on condition of anonymity.
About 17,000 troops are stationed at Fort Riley. Grigsby assumed command of the base in August 2015, after 31 years of military service that included a stint as commander of the Combined Joint Task Force in East Africa.
Grigsby was last in the news in June when Fort Riley rescinded an invitation for a retired senior military officer to speak at a prayer breakfast at the base. Retired Lt. Gen. Jerry Boykin was disinvited after complaints about his views on transgender bathrooms and Muslims.
The invitation was rescinded after Mikey Weinstein, founder of the Military Religious Freedom Foundation, protested to Grigsby, who was base commander at the time.
Boykin's invitation drew complaints because of comments he has made claiming Islam doesn't deserve First Amendment protection and remarks about transgender people that were perceived as threats.
There were no suggestions that Grigsby's current problems were related to the Boykin matter.
Prior to that assignment, he served as the deputy commanding general for maneuver of the 1st Cavalry Division. He earlier commanded the 2nd Brigade, 1st Infantry Division, at Riley and deployed with that command to serve in northwest Baghdad, according to Smith.
Martin assumes command of the Big Red One as it prepares to deploy to Iraq in support of Operation Inherent Resolve.
Martin will be succeeded at the National Training Center by Brig. Gen. Jeffery D. Broadwater. Broadwater is currently serving as the director, CJ-35, for Operation Resolute Support in Afghanistan and has had two previous tours of duty at the training center.
-- Matthew Cox can be reached at firstname.lastname@example.org.