Mezue ahịrịokwu na-esonụ: Gillman gụrụ akwụkwọ na Dulwich College, a họpụtara ya n'ọrụ Royal Field Artillery na July 1889. E buliri ya n'ọkwa lieutenant na 27 Julaị 1892, na onye isi (onye na-agbakwunye na ntọala ahụ) na 9 Ọktọba 1899. O jere ozi na Agha Boer nke Abụọ 1899-1900, ebe o sonyere na Enyemaka nke Kimberley, na agha ndị na-esote nke
Paardeberg (ọgwụgwụ February 1900), Poplar Grove, na Driefontein (March 1900). Na ngwụcha afọ 1901, ọ nọ na Ndịda Naịjirịa, ebe e kenyere ya dịka onye isi ndị ọrụ na kọlụm ndị na-ekere òkè na agha Aro-Anglo (November 1901 ruo March 1902), nke a kpọtụrụ aha ya na despatches site n'aka onye isi ndị ọrụ dịka "onye ọrụ dị oke ọnụ ahịa, dị jụụ ma jupụta na ume". A họpụtakwara ya ka ọ bụrụ Companion of the Distinguished Service Order (DSO) maka ọrụ ọ rụrụ n'oge agha. N'ọnwa Mee afọ 1902, a họpụtara ya ka ọ bụrụ onye isi nke Batrị 119 nke Field Artillery. O mechara nọrọ oge na Southern Nigeria na 1902.