Napoleon once remarked, "An army marches on its stomach". The Emperor offered 12,000 francs to anyone who could devise a way to preserve food for his beloved army. It's hard to imagine anything more sphincter-tightening than an army of Frenchmen bearing down on you reeking of champignons a la Greque. The award was won by Nicholas Appert, who didn't put his food in cans at all, but bottles. The British army responded by commissioning Peter Durand to develop 'a cylindrical canister fashioned out of tin plate to prevent corrosion': the world's first tin can.
Over the years, the design has been modified to incorporate a ring-pull. I still prefer the ceremony of using a can-opener. It's also why I prefer corks to screw-tops. It's the slight imperfections in a design that gives it character. That said, the original can-opening instructions go beyond the characterful - they instruct the user to utilise a chisel and hammer.