As in any small English village, both the First and the Second World War had significant impacts on the residents and their daily lives. The First War (1914-1918) took the lives of 24 local men whose names are commemorated on the Roll Of Honour that hangs in St. Mary's church.

Forncett History Group undertook a major project (the Forncett Great War Project), led by Jackie Scully, to research the stories of all the Forncett men lost during WWI. This led to the production of a Book of Remembrance and to a series of presentation boards that document the Timeline of the War from 1914 to 1918 that integrates major incidents in the War with the deaths of each of the Forncett men. The Great War Timeline is now on permanent display at Norfolk Tank Museum in Forncett St Peter.

As might be expected, the Second War had less impact in terms of loss of life; just four Forncett men lost their lives. However there were many other effects on the lives of Forncett residents, and probably the most significant was the construction of three airfields for the use of United States Army Air Force (USAAF) bomber squadrons all within 5 miles of Forncett.

Tibenham airfield (south of Forncett) had been used as a landing ground by the Royal Flying Corps during WWI but in 1941/42 it was expanded for the USAAF and the first servicemen arrived in November 1942. A second airfield was built in 1942 at Hethel (north-east of Forncett) and this opened for service in September 1942. Finally a third base was built in 1942/43 at Old Buckenham (west of Forncett) and this opened in late 1943.

Needless to say, the influx of thousands of American airmen didn't go unnoticed by the residents of these small Norfolk villages. Off-duty airmen used bicycles to visit local pubs where they were a great attraction to some of the local girls. The presence of hundreds of aircraft in the skies over Forncett also couldn't be ignored and from time to time aircraft crashed in the vicinity, including within the parish of Forncett.