Military displays, vintage cars, stallls and much more will be on offer at the Kirtling Tower open gardens on June 30.
Lord and Lady Fairhaven have given permission to their gardens to open to the public to raise money for ssafa, the Soldiers, Sailors, Airmen and Families Association.
The assoication which dates back to 1885, provides lifelong support to forces and their families, helping around 300 people a year.
The event takes place from 11am to 4pm. Entrance costs £5 per person while children get in for free.