A merger is "[t]he act or process of merging two or more parts into a single unit". In the context of drum and bugle corps it is the amalgamation of two separate drum corps into one performing unit. This amalgamation may include marching members, administration, support staff and instructional staff. The term is used loosely and may refer to a temporary agreement between two organizations that maintain their identities and staff throughout the merger period or it may refer to members of one corps joining another corps with a minimum of participation by their corps administration and instructional staff in the resulting unit. Usually a merger results in a new name being taken on by the new unit as an indication of the change in both units.
Mergers are often difficult to maintain and do not always result successful or viable corps. Examples of successful mergers include the Crossmen, a merger of the 507 Hornets and Keystone Regiment and the Oakland Crusaders, a merger of the Etobicoke Crusaders and the De La Salle Oaklands.