Civil War

Maine men would be called on again in 1861 when war divided the nation into North and South. The Portland Light Infantry was designated as Company A of the 1st Maine Volunteer Infantry Regiment, a 90-day regiment, and marched off to Virginia but was not engaged in the Battle of Bull Run. The 1st Maine was mustered out of service on August 5, 1861.^[1]

Many members of the 1st Maine Volunteer Infantry reenlisted as members of the 10th Maine Volunteer Infantry Regiment when it was formed in October 1861. It fought at the battles of Cedar Mountain and Antietam in 1862. Most enlistments in the 10th Maine expired on May 8, 1863, except for 3 companies of "three year men" who were retained in service as the 10th Maine Battalion. The 10th Maine Battalion served as the Provost Guard for the Army of the Potomac at the Battle of Gettysburg. The 29th Maine Volunteer Infantry Regiment was mustered into service on December 17, 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. On 29 May 1864, the 10th Maine Battalion was consolidated with the 29th Maine, thus establishing continuity with the 10th Maine Regiment and the 1st Maine Regiment. The 29th Maine served on occupation duty in South Carolina starting in June 1865 and was mustered out of service on June 21, 1866.^[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's enlistments ran up in 1863, but about half the unit had signed papers to serve for the three years, so they were amalgamated into the 20th Maine Volunteer Infantry Regiment. Also in 1862, the 20th Maine Volunteer Infantry Regiment was raised from the Brewer area. The 20th would become one of the most famous units in the Civil War. 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. They had been ordered to hold to the last man. The regimental commander, Colonel Joshua L. Chamberlain then gave the order, "Bayonet, Forward!" knowing that he could not withdraw or the enemy would outflank the Union army. The bayonet charge by the Mainers took the Confederates by surprise and ended their attacks entirely. For his actions, Colonel Chamberlain was awarded the Medal of Honor. The 20th would serve until the end of the war, fighting with distinction in the savage battles through Virginia, such as the Wilderness, Spotsylvania, and Petersburg. The 133rd Engineer Battalion carries on the lineage and traditions of the 20th Maine.^[1]

1865-1940

At the end of the war, the Soldiers came home and returned to their civilian lives. Many kept up their military experience by membership in the 1st Maine Volunteer Militia, organized in 1873. The 1st M.V.M. had companies in Portland, Augusta, Skowhegan, Auburn, Norway, Bangor, Belfast, Hampden, and Old Town, laying out the footprint for the future 133rd Engineer Battalion. In 1893, the Maine Volunteer Militia was re-designated as the Maine National Guard, and the 1st M.V.M. was designated the 1st Maine Infantry. The 2nd Maine Infantry was also brought under the Maine National Guard when it was formed from the Maine Volunteer Militia in 1893.

In May 1898 the 1st Maine Infantry was mobilized as the 1st Maine Volunteer Infantry for service in the Spanish–American War. It served stateside and was mustered out of service on 13 December 1898.^[1]

In 1909, the 1st M.V.M. reorganized and re-designated as the Coast Artillery Corps, with batteries from Bath to Kittery. In 1917 it was mobilized to protect the Maine coast, manning coast defenses, primarily near Portland. In December 1917 four companies were attached to the 54th Artillery (Coast Artillery Corps)^[1] and deployed to France, where they fought on the Marne and the Meuse-Argonne Campaigns. The remaining companies remained in Maine until they were demobilized in December 1918.

The 2nd Maine Infantry was called into service in 1916 for service on the Texas border and then again in 1917 for World War I where it was combined with a unit from New Hampshire to become the 103rd U.S. Infantry, which was one of the four Infantry regiments in the 26th Division (a.k.a. the "Yankee Division").^[1] They served on the front lines in France, taking part in the battles of Champagne-Marne, Aisne-Marne, Saint-Mihiel, Meuse-Argonne, Ile de France, and Lorraine. One soldier, Private First Class George Dilboy, was posthumously awarded the Medal of Honor for his actions in single-handedly overrunning a German machine gun position.

The 103d Infantry was demobilized in April 1919 and was reassigned to the 43rd Infantry Division when it was formed in the early 1920s.^[1]

In 1922 the Coast Artillery units were redesignated as the 1st Coast Defense Command, and re-designated again on 17 September 1923 as the 240th Coast Artillery Regiment.^[1]

World War II

As the United States prepared to enter World War II, the 240th Coast Artillery was mobilized to defend Portland on September 16, 1940. On 7 October 1944, the regiment was re-organized into the 185th and 186th Coast Artillery Battalions. On 1 April 1945, the two battalions were consolidated into the Harbor Defenses of Portland, which was inactivated in June 1946.^[1]

During World War II, the 103rd Infantry, as an element of the 43rd Infantry Division,^[1] served in the Pacific theater, fighting in the battles of Guadalcanal, North Solomons, New Guinea, and Luzon, helping General Macarthur liberate the Philippines. They were the first unit to reach the Ipo Dam, which controlled the water supply for Manila, a crucial step in liberating the city.

Post WWII

In February 1947, the Coast Artillery units were re-organized and re-designated as the 703rd Anti-Aircraft Gun Battalion.^[1] They were mobilized from August 1950 to April 1952 to replace Regular Army units that had deployed to Korea during the Korean War.

On 1 March 1959 Companies A, B, and C of the 703rd AA Bn consolidated with the 103d Infantry and were reorganized and re-designated as the 103d Armored Cavalry Regiment (ACR). Meanwhile, Headquarters and Company D of the 703rd AA Gun Bn were re-organized and re-designated, and consolidated with the 314th Anti-Aircraft Artillery Battalion to form 1st Battalion, 240th Artillery. On 1 June 1961 the 103d ACR, less the headquarters company, was reorganized and re-designated as the 20th Armor Regiment. At the same time, the Headquarters Company of the 103rd ACR was re-designated as Headquarters, 113th Armor Group.^[1]

The 240th Artillery was converted, reorganized, and re-designated on 1 June 1961 as the 262d Engineer Battalion with headquarters at Bangor.^[1]

In 1962, the 3d Battalion, 20th Armor was mobilized for the Berlin Crisis and stood ready in Fort Stewart, Georgia, until the crisis defused. 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. The 240th Coast Artillery served until the 1960s before being disbanded, but its lineage was assumed into the 20th Armor.^[1]

On 31 December 1967 the 20th Armor consolidated with Headquarters, 113th Armor Group to form the 133d Engineer Battalion.^[1]

On 1 September 1993 the 133rd Engineer Battalion was consolidated with the 262nd Engineer Battalion while retaining its designation as the 133rd Engineer Battalion.^[1]