[2][3] In August 1914, when the First World War broke out, Casey was working for the Peninsular and Oriental Steam Navigation Company.
He gained his first aerial victory on 17 March 1917, driving down out of control a Halberstadt D.II fighter over Bapaume.
On 21 April 1917, he attacked a hostile two-seater machine at a range varying from 40 to 100 yards, and brought it down completely out of control.
On 23 April 1917, on four different occasions during one flight, he attacked hostile machines, one of which was driven down in a spinning nose dive and another turning over on its side went down completely out of control.
[1][11] He is buried in Adinkerke Military Cemetery in De Panne, West Flanders, Belgium.