The Second Battalion of U.S. Engineers ceased to be on August 1st, 1916, when the Second Regiment of U.S. Engineers was organized with Headquarters at Colonia Dublan, Mexico. Therefore, as a part of General Pershing's punitive expedition, it has the honor of being the only Regiment of the U.S. Army to be organized on foreign soil.

The principal duties of the Regiment while on this expedition were roadwork and bridge building, although some deep wells were bored and several reconnaissances made. The first road was built from Columbus, New Mexico, to El Valle, Mexico, a distance of 170 miles through alkali deserts and swamps. This road was a great help to the handling of supplies. Holt tractors, which were being tested for Army use, were operated by men from the Second Engineers. Reconnaissance parties often came in contact with the enemy, thus adding a little spice to the monotony of engineer work. One day, two engineers were attacked by a large band of the enemy-fully 50 to 1. The commander of this band was the great bandit Cervantes, whose reputation was known to all. While his comrade went for assistance, one of the engineers held the party with his rifle fire. Through his training, he made the party think there were several men firing at them. When the reinforcements arrived, the band had retreated leaving several dead on the ground among whom were General Cervantes and two of his aides.

After a campaign of almost a year in Mexico, the Regiment marched back across the border into Columbus, New Mexico, on February 5th, 1917, with Regimental Colors flying at the post of honor in the rear guard. It was reviewed by General Pershing as it crossed the border. After two days in Columbus, the Regiment moved in trucks to Camp Stewart, El Paso, Texas, where it was welcomed with a dinner and smoker by the Pennsylvania Artillery. After two months in Camp Stewart, the Second Engineers moved to Camp Baker in the same city, where it did engineer work and some training in Pontooning, Railroading, Sapping, etc. While the Regiment was stationed at this place, Lieutenant Colonel James F. McIndoe took command. In May it was reorganized into the Second and Fifth Regiments, the Eighth and Ninth Mounted Battalions, and the Second Engineer Train.

While at Camp Baker, the Second Engineers went through a period of intensive training in Engineer work peculiar to the European War. The most up-to-date revetted trenches, deep dug-outs, and wire entanglements were drilled in, until August 22nd, when the Regiment left El Paso for Washington, D. C., on the first leg of its trip to France.