Tacticus
General Callus Tacticus was a soldier of the Ankh-Morpork Empire, and is widely proclaimed to be the greatest general of all time. In fact, on the Discworld the word 'tactics' was derived from his name. He has been dead for nearly 2000 years by the start of the Discworld series. In Jingo his name is given as Gen. A. Tacticus. In Wintersmith, however, his first name is given as Callus.
Tacticus conquered a large area of the Discworld, both around the city of Ankh-Morpork and well into the rimward continent of Klatch. Since his campaigns were as expensive as they were effective, the rulers of Ankh-Morpork tried to get rid of Tacticus in a respectful and appropriate way. When at one point the far-flung city of Genua, having run out of royalty of their own, asked Ankh-Morpork for a Duke, Tacticus was promoted and sent there. Immediately upon becoming a Genuan citizen, he evaluated the question of the greatest military threat posed by any single other nation. Tacticus therefore declared war on Ankh-Morpork, which (it is implied) was the reason why Ankh-Morpork lost its large empire.
When Vimes got a copy of Tacticus' autobiography from the Librarian, he formulated a characteristically cynical opinion as to why Tacticus, although respected, was not much liked by history: Tacticus didn't get a huge number of his men killed by his own arrogance and incompetence. Snippets of Tacticus' advice turns up in various Discworld chronicles, and it can be gathered that he was a very realistic, down-to-earth general. For example, the section of his autobiography entitled "What to Do When One Army Occupies a Well-Fortified Fortress on Superior Ground and the Other Does Not" begins with the sentence "Endeavour to be the one inside." Another good example of Tacticus' sense of pragmatism would be his maxim "It is always useful to face an enemy who is prepared to die for his country. This means that both he and you have exactly the same aim in mind."
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