The term "Navy Strength" originates from the 18th century when British Navy soldiers would test the quality of rum by adding gunpowder to it and igniting it. If it didn't catch fire, it was too diluted. This soon translated into gin when it became the drink of choice on board.
By definition, Navy Strength gins are all 57% ABV and due to this they have bolder juniper flavours. You have been warned!