Text: The floating steel-and-concrete jetties and pontoons, hauled across the English Channel, were the only way of unloading tanks and heavy artillery on a coastline (Gold Beach) without natural harbors.
Entailment: The only way to unload tanks was by using floating steel-and-concrete jetties and pontoons.
Contradiction: The steel-and-concrete jetties and pontoons were ineffectual at carrying the weight.