The United States Army North (ARNORTH) was a formation of the United States Army. In its final form, it was an Army Service Component Command (ASCC) subordinate to United States Northern Command (NORTHCOM), ARNORTH was the joint force land component of NORTHCOM. ARNORTH was responsible for homeland defense and defense support of civil authorities. ARNORTH was headquartered at Fort Sam Houston, Texas.
Redesignated ARNORTH in 2004, it was first activated in early January 1943 as the United States Fifth Army, under the command of Lieutenant General Mark W. Clark.
ARNORTH was officially deactivated on 15 July 2026, becoming the third headquarters to transition into the United States Army Western Hemisphere Command.
The first iteration of the Fifth Army was authorized by the National Defense Act of 1920, and was originally to be composed of Organized Reserve units primarily from the Fourth, Fifth, and Sixth Corps Areas. The Headquarters and Headquarters Company were constituted in the Organized Reserve on 15 October 1921 and allotted to the Fifth Corps Area. Columbus, Ohio, was designated as headquarters upon organization, but the headquarters was never organized at that location. The Headquarters Company was initiated in 1922 in Columbus. Columbus remained the Fifth Army's designated headquarters location upon the event of its activation until 16 July 1932 when Indianapolis, Indiana, was designated as the army's new headquarters location. Due to the abandonment of the "Six Army" plan in favor of the "Four Army" plan, the Fifth Army was deleted from mobilization plans on 1 October 1933 and demobilized (disbanded). Its subordinate units were reassigned to the Second Army, the General Headquarters Reserve, or demobilized.
The United States Fifth Army was one of the principal formations of the U.S. Army in the Mediterranean during World War II, and was the first American field army ever to be activated outside of the United States. It was officially activated on 5 January 1943 at Oujda, French Morocco and made responsible for the defence of Algeria and Morocco. It was also given the responsibility for planning the American part of the invasion of mainland Italy, and therefore was not involved in the Allied invasion of Sicily (codenamed Operation Husky), where it was instead assigned the role of training combat troops destined for Sicily. The United States Fifth Army was initially commanded by Lieutenant General Mark Clark, who would lead the Fifth Army for nearly two years, and was to experience some of the toughest fighting of World War II, where it was engaged on the Italian Front, which was, in many ways, often more reminiscent of the trench warfare of the Western Front in World War I. Writing to Lieutenant General Jacob L. Devers (American deputy to Field Marshal Sir Henry Maitland Wilson, Mediterranean Theater commander) in late March 1944, Clark explained the difficulties of the fighting in Italy so far, which could be said of the whole campaign. They were, he claimed, "Terrain, weather, carefully prepared defensive positions in the mountains, determined and well-trained enemy troops, grossly inadequate means at our disposal while on the offensive, with approximately equal forces to the defender."
The Fifth Army first saw action during the Salerno landings (Operation Avalanche), the assault landings at Salerno, part of the Allied invasion of Italy, in September 1943. Due to the comparatively low numbers of American troops available in the Mediterranean Theater it was made up of one American and one British corps. They were the U.S. VI Corps, under Major General Ernest J. Dawley and the British X Corps, under Lieutenant-General Richard L. McCreery. At Salerno, VI Corps landed on the right flank, and X Corps on the left flank. Progress was initially slow, due in part to a lack of initiative by Dawley, the VI Corps commander, and due also to heavier than expected German resistance. However, heavy naval and air bombardment, along with a parachute drop by elements of the U.S. 82nd Airborne Division, had saved the forces from any danger of being driven back into the sea, combined with the approach of the British Eighth Army, under General Bernard Montgomery (the Eighth Army had landed further south in Operation Baytown, six days before Avalanche), the German 10th Army began to retreat. On 20 September, by which time the Fifth and Eighth Armies had linked up, Major General Dawley, VI Corps commander, was relieved of his command by Clark. Dawley was temporarily made deputy army commander, and was soon replaced in command of VI Corps by Major General John P. Lucas.
Progress was then good for a couple of weeks and the Fifth Army crossed the Barbara Line and the Volturno Line until the Germans turned, stood and fought. They had established a position on the Winter Line (also known as the Gustav Line), which included the formidable defensive positions at San Pietro Infine in the Liri Valley and at Monte Cassino. By this point, Fifth Army had been reinforced by a second American corps, II Corps, commanded by Major General Geoffrey Keyes. By the end of November Clark's Fifth Army had almost doubled in size, with the addition of French General Alphonse Juin's French Expeditionary Corps, from 130,247 men to 243,827. With the failure of the first operations to capture Monte Cassino, an attempt was made to exploit the Allied preponderance in seapower before the coming invasion of Normandy robbed the Mediterranean of the naval forces necessary for an amphibious assault to seize Rome.
VI Corps, with its experience of amphibious landings at Salerno, was chosen for the assault and withdrawn from the line, replaced by the French Expeditionary Corps. They made a second attempt to capture Monte Cassino in conjunction with the amphibious assault by VI Corps, which again failed. VI Corps landed at Anzio, unopposed, on 22 January 1944 in Operation Shingle, and suffered many of the same problems as had been seen at Salerno. A perceived lack of initiative on the part of the commander, Major General Lucas, combined with worries about the Germans catching VI Corps off balance if it advanced too far inland resulted in the beachhead being bottled up. The Germans launched a series of attacks and counterattacks, with both sides sustaining heavy losses, and nearly breached the last beachhead defences before again being driven off by heavy naval and air support. The fault, however, "was not due to Lucas's incompetence; it was due instead to wishful thinking, faulty operational planning, and the German army's ability to respond forcefully and aggressively."
After the failure of Shingle, a large reorganization took place. Previously the Apennines had been the rough dividing line between Fifth and Eighth Armies. However, the dividing line was shifted westwards, to allow the concentration of both armies on the western side of Italy for maximum firepower to break through to Rome. British V Corps was left on the Adriatic coast to pin down any German units there. Fifth Army was relieved of responsibility for Cassino and the final phases of that battle saw Indian, New Zealand and finally Polish troops thrown against the fortress. Fifth Army also lost McCreery's British X Corps at this time, since it was felt that having exclusively American-organised units under Fifth Army and British-organised units under Eighth Army would ease logistics.
The breakthrough was achieved during the spring of 1944. Coordinated assaults by all the Allied forces, except V Corps, which was confined to a holding action, broke through. II Corps attacked along the coast, the French Expeditionary Corps, in a classic demonstration of mountain warfare, broke through on the right flank of Fifth Army, and VI Corps, now commanded by Major General Lucian K. Truscott, broke out of the Anzio beachhead. By early summer, Allied forces were well on their way to capturing Rome.
At this point, one of the more controversial incidents in the history of Fifth Army occurred. The strategic conception of General Sir Harold Alexander, commanding the Allied Armies in Italy (later redesigned 15th Army Group), was that the forces of VI Corps, coming out of Anzio, would trap the retreating German forces, and leave them to be annihilated by the advancing Fifth and Eighth Armies. However, in contravention of orders, Clark diverted units of VI Corps towards Rome, leaving a small blocking force to attempt to stop the Germans. It failed to do so, and the German forces were able to escape and reestablish a coherent line to the north of Rome. Clark claimed that there were significant German threats which necessitated the diversion, but many believe that he was primarily glory-seeking by being the first to liberate Rome.