At Queen's Park, archaeologist Michael Taylor showed him the only visible remain of the Rutland Stockade - some bricks placed at the junction of two former walls.
There are not many other memorials to the Land Wars in Wanganui. But another is the lion monument on the Veterans' Steps. The bones of some of those who fought in the 1865 Battle of Nukumaru were buried nearby.
The first British regiment arrived in Wanganui in December 1846 to protect the European settlers from Maori, who did not want them there. The earliest fortification on the sandhill known as Pukenamu was built of raupo.
Another regiment arrived, and the secondary York Stockade was built on another sandhill.
There were as many as 2000 British soldiers who moved up and down the coast, using Wanganui as their base. Settler numbers got as low as 200 at one time, when they were feeling threatened.
"It was a huge army presence. I think it still resonates today. It's why Wanganui has such a strong band (initially known as the Garrison Band) and wider musical traditions," Mr Diamond said.
The soldiers were mainly young and the regiments had disbanded by the end of 1870. Many of the 3600 discharged stayed on to take up land and settle. Some of their descendants, and of the Maori they fought against, are still in the district.
Some in Wanganui wanted to demolish the Rutland Stockade in the 1880s, but others were against it. They said the building was part of the town's history, and could become a tourist attraction.
But it was in poor repair, and the demolishers got their way. A few remnants of the stockade are held in Whanganui Regional Museum, and the Rutland Arms Inn was named after it. Salvaged timber was used to build the prison in Maria Pl, now the Whanganui Resource Recovery Centre.
There ought to be more evidence left of the stockade, and of the "fantastically rich" history of that time, Mr Diamond said.
"People go to Wanganui, not just mad historians like me, for the history and the heritage." That military history must shape the town still, he said, and it would be healthy to acknowledge it. But the Maori side of the story was needed as well. "Everyone has to be comfortable with being able to have a say."