After spending part of his childhood in Canada, where his father was Governor General, he attended Harrow School.

[3] Blackwood's amusing pen and ink sketches were in a style which has been described as "German expressionism",[4]: 123  and were credited only to "B.T.B.".

[5] In the rhyming introduction to the Cautionary Tales, Belloc describes Blackwood's drawings as "...the nicest things you ever saw".

[citation needed] On the outbreak of World War I, Blackwood obtained a commission as a 2nd Lieutenant in the 9th Lancers, at the age of 44.

He served as a "galloper" at the Battle of Mons and was severely wounded in October 1914 and returned to the United Kingdom.