Why Did the Royal Navy Force Sailors to Drink Rum?

Britain has gone to war over one man's ear, and you are the one who has to sail there. It is the middle of the morning in Port Royal, Jamaica, and you are standing in a queue on the deck of a British warship. The sun has been up for hours. The pitch in the deck seams is soft and sticky under your bare feet. Your shirt is glued to your back, your mouth tastes of salt pork, and you are waiting for the best moment of your day. Your rum.