One of the largest and oldest units in the Maine National Guard, the battalion has responded to natural disasters at home and undertaken military deployments overseas.

[citation needed] Other militia units flooded Portland that year, responding to a British invasion from the north that had seized Bangor and Castine.

However, American militia units from all over Maine put up such a strong defense that after a few skirmishes on the outskirts of town, the British decided that an attack would be too costly and cancelled the invasion.

The 29th Maine Volunteer Infantry Regiment was mustered into service on 17 December 1863, and was transferred to the southern theater, fighting in Louisiana in the Red River Campaign from March to May 1864, and then in Virginia from July 1864 to April 1865.

[1] The 2nd Maine Volunteer Infantry Regiment was called into service at the same time as the 1st and saw action during the Seven Days Battles, 2nd Bull Run, Antietam, Fredericksburg, and Chancellorsville.

The regiment saw limited action at Antietam but made up for it at the Battle of Fredericksburg, where they were part of the assault element that aimed to take the Confederate defenses on the high ground.

The 20th sustained heavy casualties and was pinned down for over twenty-four hours under enemy fire in the cold December weather.

They were positioned on the far left of the Union line at the Battle of Gettysburg in 1863 and sustained multiple enemy attacks until the regiment had nearly run out of ammunition.

The 1st Maine Volunteer Militia had companies in Portland, Augusta, Skowhegan, Auburn, Norway, Bangor, Belfast, Hampden, and Old Town, laying out the footprint for the future 133rd Engineer Battalion.

One soldier, Private First Class George Dilboy,[2] was posthumously awarded the Medal of Honor for his actions in single-handedly overrunning a German machine gun position.

The 103rd Infantry was inducted into active federal service at home stations on 24 February 1941 and moved to Camp Blanding, Florida, where it arrived on 13 March 1941.

[4] As the United States prepared to enter World War II, the 240th Coast Artillery was mobilized to defend Portland on 16 September 1940.

They were the first unit to reach the Ipo Dam, which controlled the water supply for Manila, a crucial step in liberating the city.

[1] They were mobilized from August 1950 to April 1952 to replace Regular Army units that had deployed to Korea during the Korean War.

In 1963, the 1st Battalion, 20th Armor was stood up in readiness during the Cuban Missile Crisis but the issues were resolved before the unit had to deploy.

After the 2003 invasion of Iraq by a United States-led coalition, the 133rd was mobilized in support of Operation Iraqi Freedom II between 2004 and 2005.

[citation needed] Similarly, the 133rd sent Joint Task Force Maine to Vermont in 2011 to assist in Tropical Storm Irene recovery.

[7] Following Superstorm Sandy in 2012, a task force of vertical and horizontal Engineers from the 133rd assisted communities in Connecticut in their recovery efforts.

[citation needed] In the spring of 2013, the 133rd deployed a company of vertical engineers to El Salvador to assist in critical infrastructure repairs in support of Operation Beyond the Horizon.

[9] Lt. Col. Lisa Sessions made history as the first woman to hold the post of commander in the Maine Army National Guard’s 133rd Engineer Battalion.

During this event, Lt. Col. Shanon Cotta handed over command to Lt. Col. Lisa Sessions, marking a significant milestone for women in leadership within the battalion.