A Mississippi Army National Guard unit with a 91-year history that includes service during two world wars is being deactivated as part of a military restructuring.

The 631st Field Artillery Brigade in Grenada was organized in April 1917 and was soon called to federal service during World War I. Members of the unit later served in New Guinea and the Philippines during World War II.

The unit will be deactivated Sept. 30.

“We’ve known for a couple of years that they were going to go away,” said Tim Powell, a Guard spokesman. “We’ve been moving troops from that unit to other units and we will continue to do so until all those troops are placed in other units.”

There are about 70 members of the unit remaining, which is down from about 120 when the deactivation was announced. Powell said the armory in Grenada, a town of about 14,900 people in north Mississippi, will eventually get a new unit or a portion of a unit.

“We have no plans to close that armory,” Powell said.

Grenada Mayor Billy Collins said Thursday that the community is proud of the 631st.

“It’s an old unit that we are certainly sorry to see leave,” Collins said. “We’re proud they’re not closing it. I don’t have to tell you the way the economy is … We’ll just have to get used to this new unit and welcome them.”

There also remains a major Guard presence in the area with Camp McCain, a 13,000-acre training base in Grenada County named for a late relative of Republican presidential candidate John McCain. Camp McCain has some 125 employees with an annual economic impact of about $8 million, according to the Grenada County Chamber of Commerce.

Guard units around the country have been restructured in recent years as the military makes adjustments meant to deal with changing needs around the world.

“These restructurings are part of our overall transition of the National Guard and other units in order to provide our nation with a lighter, more agile defense for future missions,” Powell said. “The transformation has been an ongoing part of the Army National Guard in the last several years.”

Other units in Mississippi have been restructured in recent years, according to Powell:

— The 114th Area Support Group in Hattiesburg deactivated and was re-designated as Detachment 1, 184th Transportation Support Command.

— The 1st Battalion, 114th Field Artillery in Greenwood became Company B, 2nd Battalion of the 198th Combined Arms Battalion.

— The 168th Engineer Group in Vicksburg became the 168th Engineer Brigade Headquarters.