From a letter, Hugh Gilchrist who was writing a book on early Greek-Australian contacts to PAC on 22 Oct 1982.

'In the Roll of Honour of the 'Sydneian' magazine of Sydney Grammar School, he was said to have been killed in Salonika or Bulgaria in Dec 1918, which would make him the first Australian serviceman killed in Greece. And - The Australian War Memorial have now informed me that 2nd Lieut RN Cullen was commissioned in the British Army 26 July 1915 and served in L Princess Victoria's Royal Irish Fusiliers, further, that Lt Cullen was killed early in the morning of 6 Dec 1915 (I think that must mean 1916) in an enemy bayonet charge on 'Rocky Peak' of : Kosturino Ridge' while serving with the RIF. The episode is briefly related in Cunliff's history of the RIF 1793-1950.'

The Commonwealth War Graves Commission lists him as 2nd Lieutenant, 6th Bn, Royal Irish Fusiliers. He was listed as Cullen. His grave/memorial is the Dorian memorial situated in the north of Greece. He had also served in Egypt.