More than 300 birds will be released on Saturday as part of an event to honour the role of carrier pigeons in the Second World War.
The pigeons were awarded the animal version of the Victoria Cross
The Pigeon Secrets on a Wing and a Prayer ceremony is being held at Bletchley Park in Buckinghamshire, home of the famous code breakers.
During the war, pigeons were recruited from civilian lofts for work with the Army, Navy and Air Force.
About 200,000 pigeons were supplied by private breeders to the National Pigeon Service and 50,000 were bred by the United States Army.
Between 1939 and 1945, code breakers at Bletchley Park used advanced mathematical formulas to crack German communications.
They relied on birds to relay messages to the military and even though many were wounded, most pigeons found their way back to the park.
Some were rewarded for outstanding service and received the Dickin Medal, the animal version of the Victoria Cross.
At Saturday's event, message holders that were fitted to the legs of pigeons will be displayed to the public.
A pigeon memorial and original pigeon box is also going on show and Peter Bryant, chairman of the Royal Pigeon Racing Association, will give a talk.