Around 30 people attended a centenary commemoration service for Passchendaele Day at the Wanganui RSA Club Rooms on Thursday.
A further 736 people viewed the livestream of the service on the Whanganui Chronicle's Facebook page.
The service was conducted by Reverend Rosemary Anderson and Padre Stephen Van Os and hosted by the Wanganui RSA President Graeme Paul.
The Battle of Passchendaele in Belgium during WWI is remembered as New Zealand's "greatest ever human catastrophe."
Some 846 New Zealand soldiers were killed on this one morning and about 1860 more were wounded on October 12 in 1917.
Wanganui RSA manager Kyle Dalton said the ceremony went well and he was surprised when a visitor handed him three WWI medals.
"The story goes that they came into the possession of a local family because the mother of one soldier was listed as next-of-kin by several soldiers," said Mr Dalton.
"However, after checking the New Zealand military records two of the men did in fact have their own families as next-of-kin.
"We would like to return the medals to these soldiers' families."
Two of the medals were awarded to Charles Richard Russell of Christchurch who was a member of the 9th Reinforcements, Canterbury Mounted Rifles, C Squadron and James Kent of Gisborne who was a member of the 12th Reinforcements New Zealand Field Artillery, No 3 Brigade Ammunition Column, New Zealand Expeditionary Force.
"The other medal is a British Service Star 1914-15 awarded to Private F T Burrows (1999), a member of the Cameron Highlanders," said Mr Dalton.
"We will have to search further afield for that family."
Anyone who may know the soldiers' families should contact Mr Dalton at Wanganui RSA.