The 1st Infantry Division was raised in May 1917 as the literal permanent first division under the new division structure of the US Army, which was mostly made up on the spot by General “Black Jack” Pershing. Before this, the Army only had permanent regiments and brigades; divisions were temporary units for high level administration. The 1st ID was made up of existing regiments, the 16th, 18th, 26th, and 28th Infantry Regiments and 5th and 6th Field Artillery Regiment. By the end of summer the 1st ID had shipped to France, gained a third artillery regiment, the 7th FA (and formed as a brigade), an engineering regiment, and various other units, marched on parade through Paris to improve French spirits, and deployed to trenches in a fairly quiet section of the Western Front to let the Americans get their feet wet - in 1917 the US Army had not been in a major war for over fifty years, only being involved in brushfire wars and occupations. The 1st settled into trench war and defended their sector from ordinary German activity.
The first major battle for the 1st ID was in April 1918, in Picardy, when the Germans launched a major offensive. The 1st had been spoiling for a fight, and they were sent to check the advance. On 28 May the 28th Regiment led the counterattack, at Cantigny, which had been wrapped with defensive trenchworks. The assault was expected to be against an enemy battalion; it happened to come during a relief in progress, and the 28th faced two battalions in defensive positions. The 28th captured the village in less than an hour, taking 250 German prisoners. The 28th then had to keep their gains against a fresh German assault; the repulsed the attack, consolidated the line, and held. This was the first American victory of the war, and earned the 28th Regiment the nickname “The Black Lions of Cantigny.” The World War I experience of the 1st ID continued with the capture of Soissons, clearing the St. Mihiel salient, and fighting in the last major Allied attack of the War, the Argonne-Meuse Offensive, which finally pushed into Germany, and pushed an Armistice through. Soldiers of the 1st ID received a great deal of well earned acclaim for their fighting in France, including 5 Medals of Honor.
Among the heroes of the 1st ID was a real dogface - Rags, a terrier, who became a small celebrity. Rags was adopted as mascot in 1918, after a private of the signal corps (who mistook him for a pile of rags) found him on the streets of Paris. The dog was put to work by the signal corps private delivering messages - the units at the time were connected by telephone lines, but they were routinely cut by fire. Rags routinely got the messages through, generally under fire, and despite being wounded by fragments at one point, and gassed at another: in one spectacular case Rags carried a message from a cut-off unit that called in an artillery barrage and reinforcements, in time to save the unit. He learned to salute (forward right paw to the head), take cover, and to alert when shells were coming in - the human soldiers learned to watch Rags for the alert. Rags returned to the US with the 1st ID, under mysterious circumstances, and became the post dog. He was accordingly awarded medals due to a hero of his stature, and several politicians and generals had the honor of being photographed with him. On post, Rags ate in the mess hall, toured post daily, and properly rendered honor to the flag. Rags died in 1936, age about 20, and was buried with honors in Silver Spring, Maryland.
In World War II, the 1st ID was mobilized, and by fall of 1942 was landing in North Africa to take the Germans head on. The 1st saw regular combat across North Africa, part of the successful effort to push the Axis out of Africa entirely. In 1943 the 1st was part of the invasion of Sicily, a much heavier combat than the unit had seen so far in the war. Liberating Sicily took several months, into the fall of 1943, including hard mountain fighting against determined defenders. In November 1943, with Sicily liberated, the 1st ID was withdrawn to England to rest, recover, and train for the Normandy Invasion. The 1st ID landed at Omaha Beach, where it took heavy casualties, but took the beach and slowly pushed inland, and fought its way from Normandy to Paris and from Paris to the Rhine. Once in Germany the 1st ID fought through southern Germany into Bohemia (modern Czechoslovakia) by the time the war ended.
The 1st ID spent much of the next twenty years on occupation duty and later garrison duty in Germany as part of NATO forces in Europe, rotating stateside periodically. From 1965 to 1970 the 1st ID deployed to Vietnam to conduct several operations. For the rest of the Cold War the 1st continued rotating to and from Germany.
In the Gulf War the 1st ID was one of the main line units in Operation Desert Storm, taking thousands of prisoners and capturing or destroying hundreds of vehicles in the Iraqi collapse.
Units of the 1st ID have deployed to Iraq in support of Operation Iraqi Freedom repeatedly, and to Afghanistan in 2012.