"Bill" Green was commissioned a
second lieutenant in August 1917. He completed training and was posted to 57 Squadron on 29 September 1917. He scored his first aerial victory on 6 January 1918. On 2 July 1918, Green was promoted to temporary captain (customarily accompanied by appointment as
Flight Commander). On a bombing run that 20 July, the eve of the
Second Battle of Bapaume, his flight encountered the combination of blinding rain and
Pfalz D.III scouts. He afterwards wrote to Dr. Joseph Kirkland, the father of Lieut. James Tweeddale Kirkland: ... About Kirkland and Riley, what happened was this: They were on a bomb raid which I was leading. The weather was very bad, and we had been followed around by Pfalz scouts. Just as we got to the objective and had dropped our bombs, a thunder storm burst right on top of us. The rain which followed absolutely blinded every one of us, with the result that the formation got split up. I eventually collected a few of them, and having seen them across the lines, I waited for about ten or fifteen minutes, but seeing nothing I came home to find that Kirkland had not arrived. Later on we got a report through from the line that he had been seen going down over Hunland with the Huns following. Probably his engine was hit, or something like that. We are extremely sorry as he was such a topping fellow and awfully stout, and Riley no less so. On 29 August 1918, Green scored his eighth win, only to be seriously shot about by a
Fokker biplane; however, both he and his observer escaped unscathed. He scored his final win on 19 September 1918, having scored his nine victories incidental to his duties as an
Airco DH.4 pilot. His Distinguished Flying Cross was gazetted after the
armistice ended World War I, on 3 December 1918. ==List of aerial victories==