Based on feedback from the U.S.Army, it was found that there was a need for a twin engined version of the Otter. This would lead to the creation of the Twin Otter, a plane that enjoys great success even today with commercial commuter airlines as well as the military.
The DASH-7 was the result of a perceived short-haul, commuter-airline need for a larger aircraft with similar performance to the Twin Otter; the DASH-8, still in production today and considered a resounding success, was created to fill a need for an aircraft of similar size as the DASH-8 but without Short Take-Off and Landing (STOL) capabilities.