Kind of cipher in which A becomes B, B becomes C, e.g. NYT Crossword Clue

Think of an ancient leader known for shifting things around.

?????? cipher is a substitution cipher where each letter in the plaintext is shifted a certain number of places down the alphabet.

The clue describes a type of cipher where each letter in the plaintext is shifted a certain number of places down the alphabet. This is a classic example of a ?????? cipher, named after Julius ??????, who used it in his private correspondence.

Salad creator Cardini, This puzzle's subject, in two very different ways, Political figure who foolishly ignored this puzzle's title, General who crossed the Rubicon, Kind of salad whose dressing contains anchovies