Allan and Margaret Thompson have donated a flagpole at the RSA entrance, a flag and a plaque to commemorate the crew, mostly New Zealanders, who served on the Leander class light cruiser HMNZS Achilles, and, in particular, Mr Thompson's two uncles Francis and Alexander Thompson.
The couple, who have lived in Oamaru for about 20 years, got involved "a couple of months ago" when North Otago RSA president Norm Foley was telling them about plans for a flagpole on the building on Itchen St.
They offered to pay for the flagpole, and it grew from there to include a flag and a plaque to recognise Mr Thompson's family association with Achilles and its crew.
Both of his uncles were born in Ashburton and spent their early lives there, before serving in the New Zealand Navy in World War 2. After the war, they both returned to live in Auckland.
On Saturday morning, Mr and Mrs Thompson, along with Dunedin resident naval officer Lieutenant-commander Ian Marshall, unfurled the flag on the new flagpole. Mr and Mrs Thompson then unveiled the plaque.
Achilles was best known as being part of the British naval fleet which attacked Graf Spee in the south Atlantic Ocean in December 1939. The damaged German ship put into port at Montevideo, where her captain ordered it to be scuttled.
After the unveiling, North Otago recipients were presented with their New Zealand Defence Service medals.
