The brigade received all heraldry, lineage and honors from the 45th Infantry Division, including its shoulder sleeve insignia and campaign streamers for combat in World War II and Korea.

[3] On 19 October 1920, the Oklahoma State militia was organized as part of the 45th Infantry Division along with troops from Arizona, Colorado, and New Mexico.

Oklahoma Governor John C. Walton used division troops to prevent the State Legislature from meeting when they were preparing to impeach him in 1923.

Governor William H. Murray called out the guard several times during the depression to close banks, distribute food and once to force the State of Texas to keep open a free bridge over the Red River which Texas intended to collect tolls for, even after federal courts ordered the bridge not be opened.

[7] The brigade did not participate in any overseas combat operations through the 1970s or 1980s, as the size of the active duty force negated the need for National Guard formations to be deployed during the relatively small contingencies of that period.

[5] In 1999, approximately 250 soldiers of the brigade were deployed to Bosnia in support of NATO forces seeking to stabilize the country in the wake of the Bosnian War.

[14] In March 2003, Company A was ordered from the area in and around Riyadh to the northern border cities of Tabuk and Arar, Saudi Arabia in defense of Iraqi retaliation and security of strategically redeployed Patriot Missile sites.

Company B was ordered to advance into Iraq from the Kuwaiti border to provide security for ammo caches and forward operating Patriot missile sites.

Task Force Phoenix II consisted of the Headquarters and Headquarters Company (HHC), C/1-179 Infantry Battalion for convoy and base security, HHC/700th Support Battalion for base support and convoy missions, the 136th Regional Training Institute of the Texas National Guard, 3 embedded training teams (ETT's).

In April 2004, 350 soldiers from the brigade's 1st Battalion, 279th Infantry Regiment also deployed to Joint Task Force Phoenix.

[15] The mission of Task Force Phoenix II was to 1) Embed training teams into the Afghan National Army to provide training assistance, mission support, and administrative pay support 2) Assume the duties of the Office of Military Cooperation-Afghanistan (OMC-A) 3) Establish the Kabul Military Training Center (KMTC) 4) Mentor the Central Corps Commander and Command Group 5) Establish and maintain postal operations for the eastern sector 6) Conduct convoy resupply missions and 7) Establish the Afghan National Army Supply Depot.

During this rotation, the brigade grew the size of the Afghan National Army to over 14,000 as well as fielding a corps-sized force ahead of schedule.

[16] In March 2006, the 1–180th Cavalry (still infantry in '06) deployed as part of Task Force Phoenix V. They were attached to the 41st BCT (Oregon ARNG).

The 45th IBCT deployed to Afghanistan in 2011 and reunited with the 201st Corps of the ANA, as partners this time, in combined combat operations against insurgent forces in Eastern Afghanistan[19] suffering the loss of 14 Soldiers[20] but making significant progress in disrupting and destroying insurgent operations while continuing to mentor the ANA and progressively handing off security missions to them.

On 1 September 2005, the 45th Infantry Brigade, under the command of Brigadier General Myles L. Deering, was mobilized to deploy to New Orleans, Louisiana in support of Hurricane Katrina disaster relief efforts.

The first units assigned to Task Force Oklahoma (1345 Transportation Company and HHB/1-171 Field Artillery Battalion) arrived in New Orleans within 24 hours of Hurricane Katrina making landfall on 30 August 2005.

[22] The brigade received all of the honors previously accorded to the 45th Infantry Division, including its campaign streamers, which give credit for participation in combat.