(also known as corned beef in the United Kingdom and Ireland) refers to a variety of meat made from finely minced corned beef in a small amount of gelatin. The name "bully beef" comes from the French bouilli, meaning "boiled". It is sold in distinctive, oblong cans. Bully beef and hardtack biscuits were the main field rations of the British Army from the Boer War to World War II.
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Later, with a meal inside him, and strong tea making a hideous mixture in his stomach with bully beef, he felt better still.
Cecil Scott Forester. The African Queen, p.87 (1935)
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Faith, no, he says, Frank (that was his name), ’tis all about Kerry cows that are to be butchered along of the plague. But they can go hang, says he with a wink, for me with their bully beef, a pox on it.