Between the devil and the deep blue sea
It is widely held that this lunchtime stand-by is named after the fourth Earl of Sandwich, John Montagu (1718-92). Sandwich had a multi-layered life. Aside from his title as earl of a small British town named for its sand, he headed the Royal Navy as First Lord of the Admiralty, and later became a member of the cabinet. He was also a famously avid card player.
The most popular legend goes that as the earl had so many jobs and hobbies, he hardly had time to eat. Once, while seated at a card game at the Cocoa Tree, one of 18th-century London's classiest gentlemen's gaming clubs, the earl is said to have been so engrossed in a game of cards (cribbage, some say) that he refused to pause for a meal. He asked his butler to bring him a few slices of cold meat put between two slices of bread, so that he could eat the meat without soiling his fingers.
This eating method became very fashionable, with others at the club soon asking for their meats to be served 'the same as Sandwich'.
The earl's biographer, naval historian N.A.M. Rodger, concludes in The Insatiable Earl: A Life of John Montagu, Fourth Earl of Sandwich that the earl's busy lifestyle led to his habit of eating things tucked between slices of bread. But others argue that it was because he was too busy with more sinister pursuits. As a member of a debauched brotherhood called the Friars of St Francis of Wycombe, later known as the Hell-Fire Club, the Earl of Sandwich apparently indulged in worse hobbies than cribbage. Rumours of satanic worship and orgies with prostitutes surrounded the club, and the earl kept a 'devil' baboon to frighten fellow worshippers.
Suffice it to say that the earl was a busy man, leaving him little time for petty nuisances such as victuals.
While the etymology is clearly derived from the earl's title, the invention of what we now know as a sandwich long precedes the moniker. In an article titled 'Bread and Meat for God's Sake', author Mark Morton proposes that sandwiches were simply called 'bread and meat' or 'bread and cheese', in the case of Shakespeare's The Merry Wives of Windsor, written long before the birth of the fourth earl of Sandwich.