Abatis

Obstacle or barricade made of felled trees with the branches pointing outwards.  Canadian troops used abatises against an American army in the Battle of Châteauguay in October 1813, when the Americans were marching on Montréal.

Adjutant

Officer who assists superior officers by communicating orders and performing administrative duties.

Adjutant General

Senior administrative officer of the Army.

Aide-de-Camp

Officer attached to the staff for the personal service of a general.

Aiguillette

Shoulder cord first worn by French cavalry in the 17th century.  From 1731, a blue and white aiguillette was worn by Canadian officer cadets, which earned them the nickname "Cadet à l’aiguillette".  Gold and silver aiguillettes were added to the uniforms of generals and staff officers during the Napoleonic Wars.  In Canada, staff officers also wore aiguillettes and they remain part of the uniform for aides-de-camps of the Governor General of Canada and the provincial lieutenant-governors.