An excavation on Salisbury plain has proved an unusually emotional experience for the volunteer archaeologists, as soldiers recovering from injuries received in Afghanistan have made a surprise discovery: the remains of warriors who died more than 1,400 years ago.

Led by the Defence Infrastructure Organisation (DIO) and the Army, partners from Wessex Archaeology were astonished by the haul. Operation Nightingale is an award-winning project to give soldiers new skills and interests as part of their rehabilitation. The excavation was expected to produce modest results after earlier digs had turned up empty army ration packs and spent ammunition. Instead, they revealed their ancient counterparts, including an Anglo Saxon soldier buried with his spear and what must have been a treasured possession, a small wooden drinking cup decorated with bronze bands.

Mike Kelly, from 1 Rifles, found a skeleton with its head covered by a shield. He believes the position was a sign of respect to a fallen warrior. "I have been to war myself and I can imagine what the soldier would have felt as he went into battle. Knowing that as a modern-day warrior I have unearthed the remains of another fills me with an overwhelming sense of respect."

Other finds at Barrow Clump, on Salisbury Plain – which is speckled with thousands of ancient monuments around Stonehenge – included shield bosses, spear heads, a Roman brooch, hundreds of amber and glass beads, and a silver ring, alongside the remains of 27 individuals.

The site is believed be a cemetery, created by the Anglo Saxons within an already ancient burial monument, a Bronze Age barrow dating from 2,000BC. Excavation of the area was deemed essential because it was being damaged by burrowing badgers, leaving small bones and artefacts scattered on the surface.

The soldiers were so fascinated by the project that eight are now going on to study archaeology at Leicester University.

David Dawson, director of the Wiltshire Heritage museum in Devizes, described the finds as "wonderful and amazing". He plans to include many of the discoveries in a new permanent Anglo Saxon gallery, but, in the meantime, the highlights will be placed in a temporary display.

Rowan Kendrick, of 5 Rifles, said history was his favourite subject at school. "I can't believe that when I visit the Wiltshire Heritage museum, I will be looking at artefacts that I have found."

• This article was amended on 7 August 2012 to clarify that Operation Nightingale is led by the Defence Infrastructure Organisation (DIO) and the Army.