Career
The Irish-born Callaghan was living in Texas when World War I began. He returned home to join the Royal Munster Fusiliers. He transferred to the Royal Flying Corps on 1 September 1915.
He was assigned to Number.
18 Squadron in April 1916. He promptly piloted an FE.2b to victory on the 26th, getting cr for destroying a Fokker Eindekker (though the Germans recorded no casualties).
He crashlanded near Château de la Haie because of damaged controls, to discover his observer dead, shot through the head His next posting was to Number.
2 School of Aerial Gunnery.
His final posting was command of Number. 87 Squadron in January 1918. He scored four more victories in a month, between 29 May and 28 June 1918, flying Sopwith Dolphin Number.
D3671.
On 2 July, he launched a solo attack on a large formation of German fighters, estimated to number as many as 25. He was shot down in flames by German ace Leutnant Franz Büchner.