A combustor is configured to operate in a rotating detonation mode and a deflagration mode. The combustor includes a housing and at least one initiator. The housing defines at least one combustion chamber and is configured for a deflagration process to occur within the at least one combustion chamber during operation in the deflagration mode and a rotating detonation process to occur within the at least one combustion chamber during operation in the rotating detonation mode. The at least one initiator is configured to initiate the rotating detonation process within the at least one combustion chamber during operation in the rotating detonation mode and to initiate the deflagration process within the at least one combustion chamber during operation in the deflagration mode.