9th Engineer Battalion
"Gilas"

In 2008, the 2nd Brigade, 1st Infantry Division was inactivated and reflagged as the 172nd Infantry Brigade (Separate) in Germany as part of the realignment of US forces in Germany and the transformation of the 1st Infantry Division to the modular force structure. 9th Engineer Battalion remained in Germany and was reassigned to the 172nd Infantry Brigade (Separate).

Previously, the 9th Engineer Battalion was a divisional mechanized combat engineer unit, composed of 3 line companies and a headquarters company. Its mission was to provide moblity, counter-mobility, and survivability support for the 2nd Brigade, 1st Infantry Division with well trained Combat Engineers ready to deploy anywhere at any time. Its mission had been to deploy to designated contingency areas and conducts combat and/or stability operations in support of the 2nd Brigade Combat Team (not to be confused with the modular brigade combat team), 1st Infantry Division.

The 9th Engineer Battalion was constituted 15 May 1917 in the Regular Army as the 2nd Battalion, Mounted Engineers. The Battalion was organized on 21 May 1917 at Camp Newton D. Baker, El Paso, Texas. It was reorganized and redesignated in July 1917 as the 9th Engineers (Mounted) in July 1917. The 9th Engineers spent the first years of its history in El Paso serving at Camp Stewart, Texas. The unit was assigned on 27 November 1917 to the 15th Cavalry Division.

After World War I, the 9th Engineers was relieved on 22 May 1919 from assignment to the 15th Cavalry Division. The Battalion was inactivated except for A Company on 1 October 1921 at Fort Sam Houston, Texas. Company A was transferred to Fort Riley, Kansas to provide engineer support to the Cavalry School. The unit was assigned on 24 March 1923 to the 2d Cavalry Division. From 1923 to 1930, A Company provided vital training and infrastructure support to the Cavalry School as a unit of the 2nd Cavalry Division. Company A was inactivated on 19 April 1930 at Fort Riley, Kansas.

Following the outbreak of World War II, the Battalion was activated on 1 November 1941 at Fort Riley, Kansas. It was reorganized and redesignated on 15 July 1942 as the 9th Armored Engineer Battalion and concurrently relieved from assignment to the 2nd Cavalry Division and assigned to the 9th Armored Division. The Battalion landed in France in September 1944 from their staging base in England. The 9th Armored Engineers supported the 9th Armored Division's movement across France, making first contact with the enemy in the Schoenfels-Wilwerdange-Bissen area. The Battalion fought in the Battle of the Bulge in December 1944, with C Company figuring prominently in the holding of Bastogne, for which the Company was awarded the Distinguished Unit Citation.

On 7 March 1945, during the allied offensive to the Rhine River, Combat Command B of the 9th Armored Division arrived at the town of Remagen only to discover that the Ludendorf Bridge over the Rhine was still intact. A small detachment from B Company braved enemy fire to cut wires and dismantle charges set to destroy the bridge. Although several charges were detonated, the enemy failed to destroy the bridge, and B Company moved to secure the far side of the bridgehead. The following day, C Company successfully kept the bridge open despite a continuous and intense attack by artillery and aircraft that scored 24 hits on the structure. When the smoke of the battle had cleared, the 9th Armored Engineers had been instrumental in the establishment of the first bridgehead across the Rhine River since the Napoleonic Campaigns.

The 9th Engineers participated in the final sweep into Germany and after the surrender, established its occupation headquarters in the Bavarian city of Bayreuth, with A Company at Coburg, B Company at Kulmbach, and C Company at Hof. Occupation duty ended in late 1945, so the Battalion departed Germany. After returning from Europe, the Battalion was inactivated on 13 October 1945 at Camp Patrick Henry, Virginia.

The Battalion was redesignated on 17 December 1951 as the 9th Engineer Combat Battalion and relieved from assignment to the 9th Armored Division. It was activated on 21 January 1952 at Fort Lewis, Washington. The unit was redesignated again on 10 June 1953 as the 9th Engineer Battalion. In fall 1956, the 9th Engineer Battalion replaced the 35th Engineers at Kitzingen, Germany and moved to Aschaffcnburg within the year.

The 9th Engineer Battalion returned to combat in 1990 in support of Operation Desert Shield, and then participated in Operation Desert Storm in 1991, leading the 1st Infantry Division through the Desert Breach and assisting in the liberation of Kuwait. The Battalion subsequently returned to Aschaffenburg, Germany where it was assigned on 16 October 1991 to the 3rd Infantry Division.

The Battalion was inactivated on 15 August 1992 in Germany and relieved from assignment to the 3rd Infantry Division. It was assigned on 16 February 1996 to the 1st Infantry Division and activated in Schweinfurt, Germany. In October 1996, it deployed with the 2nd Brigade Combat Team (not to be confused with the modular brigade combat team), 1st Infantry Division as part of the covering force for Operation Joint Endeavor and Operation Joint Guard in Bosnia-Herzegovina. The Battalion returned to Schweinfurt, Germany in April 1997.

The Battalion later deployed to Kosovo in June 1999, as part of Task Force Falcon. The Battalion returned to Schweinfurt, Germany in December 1999.

As part of the reflagging of the 2nd Brigade, 1st Infantry Division as the 172nd Infanty Brigade (Separate), the 9th Engineer Battalion was relieved from assignment to the 1st Infantry Division and reassigned to the 172nd Infantry Brigade (Separate).