Marks Hall, a Jacobean mansion between Colchester and Braintree in Essex, served as a wing-level and command-level HQ for the US Eighth and Ninth Air Forces between December 1942 and September 1944.

Part of its estate’s deer park had been requisitioned in 1941 to build Earls Colne airfield, which came under USAAF control as Station 358 in the spring of 1943.

The mansion (known as USAAF Station 160), along with its immediate grounds, was selected in 1942 as headquarters for the 4th Bombardment Wing (4BW), one of five such supervisory units the Eighth Air Force planned to bring to the UK.

[The other four original Wing HQs were Brampton Grange (1BW) near Huntingdon; Old Catton (2BW) near Norwich; Elveden Hall (3BW) near Thetford – and Stisted Hall (5BW), which was just a few miles west of Marks Hall. In the event, the 5th Bomb Wing did not join the Eighth Air Force and was diverted to the Twelfth Air Force in North Africa, with Stisted Hall transferring to British military control.]

The 4th Bomb Wing, under Brig Gen Frederick L Anderson, began missions with B-17 'heavy' bombers in May 1943. Its early constituent bomb groups (BGs) included the 94th at Earls Colne, the 95th at Horham, the 96th at Andrews Field (Gt Saling), the 100th at Thorpe Abbotts, Norfolk and the 390th at Parham, near Framlingham, Suffolk.

The following month the Wing and its groups swapped bases with the 3rd Bombardment Wing (3BW), whose HQ then moved into Marks Hall from Elveden Hall, Suffolk.

Taking over existing and new airfields in Essex for its nascent force of B-26 Marauder ‘medium’ bombers, the 3BW began flying in tactical roles at altitudes around 12,000ft – half the height of the B-17s and B-24s – from July 1943. Earlier attacks at even lower altitudes (on targets in Holland) had incurred heavy losses among Marauders of the Wing's 322nd Bomb Group.

That autumn the 3BW was absorbed into the US Ninth Air Force which, newly arrived from North Africa, now oversaw tactical bombing missions in France and the Low Countries in preparation for the Allied invasion planned for 1944.

Under this reorganisation, Marks Hall became the headquarters of the US Ninth Air Force's IX Bomber Command on October 16th 1943, led by Maj General Samuel E Anderson. Construction of additional hutted facilities (including messes, a dispensary and extra accommodation) was completed by a US Corps of Engineers unit by early 1944.

Marks Hall would eventually control more than 25,000 personnel at 11 airfields across Essex (including three equipped with A-20 ‘light’ bombers) by D-Day, June 6th 1944.

Around 1,000 personnel, including some 120 US Women’s Army Corps members (WACs), were serving at the site by D-Day.

The facility was unusual among such HQ units in being co-located with an operational airfield (Earls Colne; 323rd Bomb Group), although they functioned independently.

Marks Hall also hosted a detachment of the USAAF's 4th Combat Camera Unit, whose output included much of the extant film footage of IX BC missions available today online.

In addition, IX BC's public relations unit at Marks Hall oversaw occasional inclusion on bombing missions by noted US journalists – among whom were Walter Cronkite and Ernie Pyle.

Gen Samuel Anderson and his HQ team moved to Chartres in France in September 1944 – when IX BC was redesignated as the 9th Bombardment Division.

In October, Marks Hall became headquarters of the Royal Air Force's No 38 Group, which controlled Halifax and Stirling squadrons, based at Essex and Suffolk airfields, in support of army and clandestine Special Operations Executive (SOE) missions.

No 38 Group's squadrons also towed troops in gliders across the Rhine as part of Operation Varsity on March 24th, 1945.

The mansion was demolished in 1950, but today Marks Hall Estate’s gardens and arboretum attract thousands of visitors annually. The 200-acre site includes a memorial to the units that served at the adjacent Earls Colne airfield.