Mr Davis "just peacefully drifted away" at a nursing home in Stoke Hammond, Buckinghamshire, yesterday at 11.15am, said his son Ken.
His father was "just worn out," he added.
Mr Davis who escaped the bloody battle of the Somme in 1916 because he contracted trench fever was the oldest survivor of the war, said the World War One Veterans' Association.
But the horrors of the trenches remained with Mr Davis throughout his life, his son said, adding: "He always expressed the opinion of how futile war can be.
"He used to say 'So many soldiers go to their deaths in a war, and in many cases for what reason?' He really abhorred war."
Despite his age and increasing frailty the wheelchair-bound Mr Davis was excited that in April he achieved his ambition to meet the Prince of Wales, the commander-in-chief of his old regiment.
They met at the Kew Gardens reunion of the World War One Veterans Association, which now has just 34 members.
Mr Davis had also been looking forward to meeting the Queen at a Buckingham Palace Garden Party this week.
His son said: "He never had any negative views and he was always positive about life, even though he was quite weak and frail.
"When I said he might meet the Queen he said 'Yes, I will go as long as the weather is fine'. Sadly he did not make it."
A spokesman for the Prince of Wales said: "The Prince of Wales felt incredibly honoured to meet Mr Davis and very much enjoyed talking to him about his life.
"The Prince will be greatly saddened to hear of Mr Davis's death."