The contra-rotating rotors eliminated the need for an anti-torque vertical rotor, allowing all power to be used for lift and thrust. Its top speed of 170 knots (196 mph, 315 km/h) was faster than 1960s, and even many contemporary, utility and attack helicopters. Its primary roles included troop movement, artillery emplacement and battlefield resupply. There is a wide loading ramp at the rear of the fuselage and three external-cargo hooks. Chinooks first saw extensive use during Second World War by both Allied and Soviet as infantry transports and ordnance delivery units.