Guests included representatives from the Malaya and Borneo Veterans Association, the Merchant Navy Association and the War Memorials Trust. Cadets from The King's School, Grantham, the 47F Grantham Squadron Air Training Corps, and the Scouts were also in attendance.
Civic dignitaries from South Kesteven and neighbouring authorities, including SKDC Deputy Leader Cllr Kelham Cooke, Mayor of Grantham Cllr Adam Stokes and the Sleaford and North Hykeham MP Dr Caroline Johnson, were all welcomed by South Kesteven District Council's Chairman Cllr Jacky Smith.
Father Stuart Cradduck, Rector of St Wulfram's Church led the prayers, which were followed by a speech from the regimental second-in-command at Prince William of Gloucester Barracks, Major Geordie Chisholm.
Major Chisholm explained that the work of the UK Armed Forces was increasing and evolving.
He said: "The world has always been a dangerous place, but it is becoming increasingly more uncertain.
"It is important that UK society and the UK population understand the role of the Armed Forces and, therefore, support them and their mission. Armed Forces Day and this flag-raising ceremony is one way for UK society to continue to connect with the Armed Forces and recognise their contribution."
Following the sounding of the Last Post by bugler Kacper Batty from The King's School, a minute's silence was observed, and the flag raised to the sound of Reveille.
The flag will fly until National Armed Forces Day on Saturday, 29 June.