Thousands of prisoners were captured and brought back to Britain where they were incarcerated during the conflict with Napoleon from 1803 to 1815. But Mr Walling, 45, a software consultant, knew nothing of this when he looked out of the window one day and saw two policemen in his garden talking to the builder.
He went outside and was shown about 40 bones. For a heart-stopping moment the couple, who have two teenage daughters, feared they were at the centre of a mystery worthy of their favourite crime drama, Silent Witness.
Mrs Walling, 42, who works in sales, said: "It was a huge shock. We are huge fans of the TV programme but we certainly did not expect to find bodies buried in the garden.
"Our builder had found some bones. At first he thought they were animal remains but then he found a larger bone and guessed it was human - he called his boss, who told him to phone the police."
A crime scene forensic officer was unable to date the bones so he sent them to Southampton University to be examined by archaeologists.
The couple's new-build property is near Portchester Castle, where around 7000 French prisoners were held during the Napoleonic Wars because existing jails were full.
Archaeologist David Hopkins, of Hampshire council, said the Wallings' home also lies about 100 yards from the site of a prison hospital from the conflict. Similar burials were found nearby 30 years ago.
Captured Frenchmen were held on ex-Navy ships in nearby Portsmouth harbour, from the 1770s to 1850s.
Many died from diseases, but it is not known how those in the Wallings' garden met their fate.
Mrs Walling said: "The archaeologist asked us whether we would allow them to rebury the bones in the garden and we agreed. Now we have got used to the idea, we are quite excited about it.'
- Daily Mail