To get a proper perspective on the organizations comprising the Iron Division, it is necessary to go back a few years in the history of the National Guard, before the various reorganizations to which it was subjected. The division was a product of gradual growth since the Spanish-American War. After that brief conflict, the National Guard of Pennsylvania set out upon a new course of development almost as a new organization.
In 1916, it consisted of four infantry brigades of three regiments each; one regiment of artillery; one battalion of engineers; one battalion of signal troops; two field hospitals, three ambulance companies and one regiment of cavalry.
The call for service in the threatened war with Mexico, resulting in a tedious tour of duty at Camp Stewart, Texas, on the Mexican border, caused lively recruiting and the upbuilding of the units. This was nearly offset on the return home by the eagerness of officers and enlisted men, disgusted with the fruitless task assigned them on the border, to get out of the service. When America entered the war against Germany, however, recruiting again livened up, but in the meantime the tables of organization of the whole army had been so changed and the regiments so enlarged that it was necessary to send quotas of selected men to fill the ranks to the required strength.
During the service on the Mexican border, a brigade of artillery had been formed and the number of infantry brigades was reduced to three. Also, a start was made on the work of expanding the engineer battalion into a regiment.
The division moved into camp at Augusta, Ga., from August 20 to September 15, 1917. The post was known as Camp Hancock. Here the drafts of selected men were received and the division was completely reorganized to conform to the new army standards. New designations also were awarded the units. It was necessary to reduce the number of infantry brigades to two, of two regiments each. The First Infantry Regiment, of Philadelphia; the Tenth, of Philippine fame, hailing from counties in the southwestern part of the state; the Sixteenth, centering in the oil country of the northwest, and the Eighteenth, of Pittsburgh, were chosen as base regiments, to retain their regimental organizations virtually intact.
The Thirteenth Infantry Regiment, of Scranton and vicinity, was broken up and its officers and men turned into the First to bring the companies up to the required strength. In the same manner, the Third, of Philadelphia, was consolidated with the Tenth; the Eighth, from Harrisburg and vicinity, with the Sixteenth, and the Sixth, from Philadelphia and surrounding counties, with the Eighteenth.
The former First and Thirteenth became the 109th Infantry, in the new designations; the former Third and Tenth, the 110th; the former Sixth and Eighteenth, the 111th, and the former Eighth and Sixteenth, the 112th.
The former First Artillery, whose batteries were distributed through the state from Pittsburgh to Ph[oe]nixville, became the 107th Field Artillery; the historic old Second Infantry, transformed into the Second Artillery during the border duty, whose home station is Philadelphia, became the 108th Field Artillery. The Third Artillery, which had been formed from the former Ninth Infantry, of Wilkes-Barre and the surrounding anthracite towns, became the 109th Field Artillery.
The cavalry regiment disappeared. One troop, from Sunbury, remained cavalry, being attached to division headquarters as Headquarters Troop. The rest were scattered through different organizations. The 103d Trench Mortar Battery was formed almost entirely from among the cavalrymen, largely members of the famous old First City Troop of Philadelphia.
The engineer regiment became the 103d Engineers, the signal troops the 103d Field Signal Battalion, and the field hospitals and ambulance companies became parts of the 103d Sanitary Train. In addition, there were formed the 103d Military Police, the 103d Ammunition Train, the 103d Supply Train, and the 107th, 108th and 109th Machine Gun battalions.