Members of the armed forces joined together in the shadow of Cardiff Castle to mark Armed Forces Day
Cardiff has officially accepted an invitation to host the second annual Armed Forces Day celebrations in 2010.
The Prime Minister made the announcement as events were held to mark the first ever day to honour all armed forces members, past and present.
This year's national event host city is Chatham, Kent, while other fun days and services are being held across the UK.
A Spitfire fly-past and a display from the Red Devils parachute team are among the events in Cardiff's Cooper's Field.
The Lord Mayor of Cardiff, Councillor Brian Griffiths, said it was "an honour and a privilege" for the Welsh capital to be chosen as the host city of the 2010 Armed Forces Day.
Gordon Brown attended the Armed Forces Day celebrations in Chatham
"Hosting next year's event gives Cardiff and the whole of Wales the opportunity to pledge our support to the brave men and women who not only served our country in the past but continue to do so today," he said.
"Wales has a very strong military history with Cardiff housing the 3rd Battalion of the Royal Welsh at Maindy Barracks.
"Plans have already begun to make next year's event something of which both Wales and the UK can be justly proud."
Next year will also see Cardiff Castle open a brand new Museum of the Welsh Soldier.
The museum has been developed by the Queen's Dragoon Guards and Royal Regiment of Wales and will open to the public from next Spring.
Plans have already begun to make next year's event something of which both Wales and the UK can be justly proud
Councillor Brian Griffiths, Lord Mayor of Cardiff
Gordon Brown revealed Cardiff's role as 2010 host of Armed Forces Day while attending the celebrations in Chatham.
In Cardiff, the Armed Forces Minister Bill Rammell extended the invitation from the Ministry of Defence when he attended events in Cooper's Field.
"It's a real attempt to recognise what the military do - those veterans in the past, those serving currently and those who will serve in the future," said Mr Rammell.
"I've visited our forces overseas and seen their absolute dedication and professionalism and you can see from the turnout today that people appreciate that effort."
There were parades and music from military bands
He added that while Armistice Day was a time to remember the mental and physical impact on veterans, Armed Forces Day was for celebrating.
"Today is a day of fun, pride and spectacle, and all of us connected to the armed forces are delighted with the country's response."
The 2010 Armed Forces Day flag was also brought to the city by the RAF Falcons Parachute Display Team, who were entertaining the crowds in Cardiff.
A Spitfire fly-past was also being held, while veterans were taking part in a parade in the city.
Armed Forces Day was established to recognise the work and bravery of all serving troops, veterans, recruits and their families.
Prime Minister Gordon Brown gave his backing to the day last year, when he said it should be "a special day of celebration".
The idea for such a day was also supported by senior military commanders and some families of service personnel killed in war.
Events, parades and services are being held across the country, including in Pontypridd, Bridgend and Tredegar.
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