He died on Monday, aged 92, after a brave battle with cancer.
Today First Minister Rhodri Morgan paid tribute to Mr Peters, saying Wales could “take pride in his memory”.
Mr Peters was born in Archer Terrace, Penarth, in 1914 and was the youngest of nine children.
He left Wales to find work in Canada when he was just 16 and was working as a deckhand when he learned about the war in Spain.
He volunteered to fight for the democratically-elected government against the military uprising led by General Franco and supported by Hitler. The volunteers were called the International Brigades and around 150 went from Wales.
However, in July 1937, he was badly wounded and transferred from the frontline. As casualties were so high in his former unit, Bob says if he had stayed on the battlefield he would have been killed.
When Mr Peters was shot, medics could not at first remove the bullet as it was too near his spine.
However, he recovered to become a motorcycle despatch rider, taking messages to the frontline. While riding on rough roads the bullet moved and it was cut out. In October 1938, the International Brigades were withdrawn. Although the war was lost they were treated like heroes.
During the Second World War Mr Peters served in the British army in Sicily, Italy and Yugoslavia. He later settled in Kent where he worked as a fork-lift driver.
His wife Frances died in 1990 and Rodney, the eldest of their four sons, died last year.
First Minister Rhodri Morgan said: “Bob’s death is almost the closing page of the history of Wales and the Spanish Civil War – one of the great ideological dividing lines of the 1930s; his was a life charted not only by unemployment, hunger and the other necessities that guide working people everywhere but also by his commitment to fight for his socialist principles.
“We all take pride in his memory and pay our respects for his contribution, and send our strongest sympathies to his family.”