The first memorial, a five-ton block of Aberdeenshire granite, sited close to the Armed Forces Memorial at the centre of the Arboretum, bears a bronze plaque inscribed with the badges of the regiment.
The monument was dedicated by the Reverend Iain May, minister of South Leith Parish Church and Chaplain to the Association.
The stone supplements the main regimental monument that is located below The Mound in West Princes Street Gardens dedicated in 1953 and updated in 2008.
The choice of The National Memorial Arboretum for this additional memorial was to commemorate all former members of the regiment, including many from overseas, and highlight the regiment’s service as The British Army’s senior and oldest infantry regiment before it was merged into The Royal Regiment of Scotland in 2006.
After the dedication, the attendees joined hundreds of other representatives from the Royal Navy and other regiments and corps for a service dedicating a memorial to the 828 prisoners of war (POWs) who died 79 years ago in the sinking of the armed Japanese freighter Lisbon Maru in 1942 while carrying 1,816 British POWs from Hong Kong to Japan.
Included amongst the POWs on board were 373 members of the 2nd Battalion The Royal Scots, who had become POWs upon the surrender of Hong Kong on Christmas Day 1941.
Dr Iain Gow, from Musselburgh, is the son of Private James Gow, who survived the Lisbon Maru sinking.
Private Gow was a POW in Kobe Camp, forced to work in the Docks. On repatriation, he remained in The Royal Scots.
Dr Gow said: “When we were growing up, like most far-east POWs, dad never really talked about his experiences.
"We knew vaguely he’d been in Hong Kong, on the Lisbon Maru, and Kobe, but not the extent of the horror he’d experienced or witnessed.”
President of the Royal Scots Regimental Association, Brigadier George Lowder, said: "After two years of planning, it is great to see this project come to fruition. It is a fitting memorial to all Royal Scots and especially poignant to be unveiled on the same day as the Lisbon Maru memorial."