Further adaptations quickly followed. The Republic P-47 Thunderbolt mounted a powerful engine that allowed it to carry large loads, this made it suitable in the fighter-bomber role as well as giving it the ability to carry large fuel tanks. Finally, the extremely high efficiency of the laminar-flow wing on the Merlin-powered North American P-51 Mustang gave it unparalleled range even on internal fuel, and with external tanks, it could cover most of Europe. Although not designed for the escort role, the P-51 remains the canonical example of the class.