Before moving on to British Army doctrine in the ETO (European Theater of Operations), it may be helpful to review the organization and leadership of the Supreme Headquarters, Allied Expeditionary force, which controlled the Allied ground forces that fought in that theater.

The Establishment of SHAEF    

The predecessor organization for SHAEF was the Allied Forces Headquarters (AFHQ) formed in August 1942 in Algiers to direct the Mediterranean theater of operations.  This was the first Allied inter-service headquarters with inter-service command and staff positions filled equally by American and British personnel.  American General Dwight D. Eisenhower was its first commander and under his leadership it became a very successful, nationally integrated  headquarters.

Above — General Dwight D. Eisenhower, Commander, Allied Expeditionary Force in the center.  From Eisenhower’s left: General Sir Bernard Montgomery, Commanding General, British 21st Army Group and initial commander of Allied Land Forces; Air Chief Marshal Sir Trafford Leigh-Mallory, Allied Air Commander, Expeditionary Force; and Lieutenant General Walter Bedell Smith, Chief of Staff to General Eisenhower.  From Eisenhower’s right: Air Chief Marshal Sir Arthur W Tedder, Deputy Supreme Allied Commander, Allied Expeditionary Force; Admiral Sir Bertram H Ramsay, Allied Naval Commander in Chief, Expeditionary Force; and Lieutenant General Bradley, commander US 12^th Army Group

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SHAEF was established for the command and control of integrated allied ground, naval, and tactical air forces (and the US and British strategic air forces from 14 April to 14 September 1944) in the ETO, beginning with planning and preparations for Operation Overlord, the    D-Day invasion of German-occupied Northwest Europe.  General Eisenhower was appointed as its commander in December 1943 and SHAEF headquarters was activated in February 1944.  In addition to bringing the AFHQ model for SHAEF, Eisenhower brought several key personnel from AFHQ including British Air Chief Marshal Arthur W. Tedder who served as the SHAEF deputy commander, and American General Walter Beedle Smith who served as the SHAEF Chief of Staff (COS).

SHAEF also subsumed an existing staff in England, called the Chief of Staff to the Supreme Allied Commander (COSSAC), led by British Lieutenant General Frederick Morgan, which had initiated planning for the invasion of the Continent and was intended to become the core of SHAEF’s G-3 Division (Operations).  General Morgan served as the initial Deputy Chief of Staff (DCOS) of Operations.  Morgan and the four additional DCOS for Personnel (G-1), Intelligence (G-2), Supply (G-4) and Civil Affairs (G-5) reported directly to the SHAEF COS.   All SHAEF offices, except the Adjutant General, had British deputies if commanded by an American, and vice versa. 

In addition, Naval Commander-in-Chief (Admiral Bertram M. Ramsay) and Air Commander-in-Chief (Air Chief Marshal Trafford L. Leigh-Malory) reported directly to Eisenhower, with their respective staffs coordinating with the Joint Planning Staff that reported to the SHAEF DCOS (J-3).

Operation Overlord was carried out by the British 21^st Army Group, commanded by General Bernard L. Montgomery.  This army group initially was comprised of the British Second Army under Lieutenant General Sir Miles Dempsey and the US First Army under Lieutenant General Omar Bradley.  After a sufficient lodgment area had been secured and follow-on forces arrived, Montgomery would become the Allied Ground Forces Commander-in-Chief, and General Bradley would assume command of the newly activated US 12th Army Group consisting of the US First and Third Armies.  

SHAEF was a large HQ that grew over the course of the European campaign from over 4,900 in July 1944 to over 16,300 in February 1945.  However, by the end of the war the number of British personnel assigned to SHAEF had been reduced to just 6,320 due to severe manpower shortages.

The Allied Contribution of Ground Forces

Britain made significant contributions to the Allied war effort.  These included thwarting Luftwaffe bombings and German U-Boat attacks on Britain’s sea lanes from the New World and its Empire.  Though it all, Britain provided a solid base from which the Allies could invade northwest Europe.  Although war weary and having suffered great losses since 1939, the UK was able to provide considerable air and power sea to the invasion, as well as  ground forces second only to those of the US and the Soviet Union.

Army Groups The Western Allies eventually would form three Army Groups western Europe.  From north to south, these were the British 21^st, the US 12^th, and the US 6^th Army Groups.  

The British 21^st Army Group was the most inter-allied army with British, Canadian, Polish Czech, Dutch, Belgian, and even American troops assigned to it for short periods.  Two armies, the British Second and Canadian First, were also joined by the US Ninth Army from 20 December 1944 to 4 April 1945.

The United States fielded two army groups, the largest being the US 12^th Army Group with the First, Third, and Ninth Armies.  Several times the US Ninth Army was attached in part or whole to the British 21^st Army Group to increase its offensive capability. Lastly, the US 6^th Army Group on the right (south) was comprised of the US Seventh and French First Armies. 

Corps Within these seven armies, four corps were provided by the British, two each by Canada and France, and thirteen corps — nearly two-thirds of all corps — by the US.

Divisions Twenty-six Allied armored divisions were divided among the 21 corps.  The British contributed four armoured divisions (including one comprised of armored engineer vehicles), one Polish, and two Canadian armored divisions for a total of seven.  Sixteen American armored divisions deployed to the ETO (although three experienced only very short periods of combat), while France fielded three more.  Therefore, while the US provided nearly two-thirds of the armored divisions, Britain provided just 15 percent.  (Note: Not included in the count are separate British armoured and tank brigades; however, the separate tank battalions fielded by the US Army more than matched the size of British armored force.) 

Due to the compartmented terrain of Western Europe and the lethality of WWII combat, infantry was always in short supply in all of the armies.  Ten British infantry divisions fought in the ETO, although two were withdrawn and broken up to provide replacements on 8 October and 12 December 1944.  Therefore, at the end of the war in Europe Britain had only eight active infantry divisions.  Canada eventually consolidated all three of its infantry divisions in the ETO.  Nonetheless, by the end of the war the British and Canadians had only eleven active infantry divisions.  Thirty-nine US infantry divisions saw service in the ETO. The French army fielded seven infantry divisions including one mountain and one motorized.  At the end of the war there were fifty-seven Allied infantry divisions in the ETO, of which only 18 percent were provided by Britain and Canada; 70 percent were from the US Army.

Britain initially provided two airborne divisions, one of which was destroyed at Arnhem in September 1944.  Four airborne divisions were fielded by the US in the ETO, providing 80 percent of the airborne divisions available in the ETO.

Why Contribution of Forces Mattered

In all, Britain never provided more than 16 of the 90 Allied divisions (18 percent) that were active the ETO; adding the eventual five Canadian divisions and one Polish division increased the contribution of the British 21^st Army Group to 24 percent.  With the US contributing 59 divisions — 66 percent of the total Allied number, it was obvious that Eisenhower justifiably could eventually replace Montgomery as the ground forces commander with an American.  As will be seen, when this occurred on 1 September 1944, this would not be well received by Montgomery.