Excerpt from The Death of Caesar by Barry Strauss, plus links to reviews, author biography & more

In any case, young Decimus found his way to Caesar's staff. The military suited Decimus. By hitching his wagon to Caesar's bright star he restored his family's name for armed might. He was Caesar's man as much as any Roman was.

We don't know what Decimus looked like. He might have been attractive like his mother, a well-known beauty, and as tall as one of the Gauls whom he once impersonated. The dozen of Decimus's letters that survive mix the coarse atmosphere of the camp with the formal politeness and self-assurance of a Roman noble. Elegant at times, his prose also includes clumsy phrases like, "just take the bit between your teeth and start talking." Perhaps some of the roughness of his gladiators—Decimus owned a troupe—rubbed off on him but, if so, it didn't stop him from trading pleasantries with Rome's greatest orator, Marcus Tullius Cicero.

In Gaul, Decimus joined the greatest military adventure of his generation. It took Caesar only eight years (58–50 B.C.) to conquer the big, populous, warlike region that the Romans called "Long-Haired Gaul," after the flowing tresses of its people—an area that comprised most of France, all of Belgium, part of the Netherlands, and a sliver of Germany (the Provence region of France was already a Roman province). (He also invaded Britain.) With its gold, agricultural produce, and potential slaves, Gaul made Caesar the richest man in Rome. He shared the wealth with officers like Decimus.

After his victory at sea off Brittany in 56 B.C., Decimus next appears in 52 B.C., when a great Gallic revolt almost broke Roman rule. Decimus took part in the most dramatic day of the war at the siege of Alesia (in today's Burgundy). As Caesar tells the story, Decimus began the countercharge against a Gallic offensive and Caesar followed, conspicuous in his reddish purple cloak. The enemy collapsed and the war was over except for mopping-up operations the following year.

In 50 B.C. Decimus was back in Rome for his first elective office—quaestor, a financial official. That same year, in April, Decimus married Paula Valeria, who came from a noble family. There was scandal here to wink at because in order to marry Decimus she divorced her previous husband, a prominent man, on the very day he was scheduled to come back from service in a province abroad.

A year after Decimus and Paula married, in 49 B.C., civil war broke out between Caesar and his oligarchic opponents. They considered him a power-hungry, populist demagogue who threatened their way of life. He found them narrow-minded reactionaries who insulted his honor—and no one paid more attention to honor than a Roman noble.

Caesar's chief opponents were Pompey and Cato. Pompey the Great—Cnaeus Pompeius Magnus—was no ideologue; in fact, he was Caesar's former political ally and son-in-law. A conqueror whose career took him to Hispania, Roman Asia (modern Turkey), and the Levant, Pompey was Rome's greatest living general until Caesar. Marcus Porcius Cato, also known as Cato the Younger, was a prominent senator, loyal to the old-fashioned notion of a free state guided by a wise and wealthy elite. Rigid and doctrinaire, he was mocked for thinking that Rome was the Republic of Plato when others regarded it as the Sewer of Romulus. He was Caesar's archenemy.

Most of Decimus's family tended to sympathize with Pompey and Cato, and his wife's brothers fought for them. As an adult, Decimus was adopted into the family of Postumius Albinus, a patrician clan that claimed an ancestor opposed to Rome's kings, and his adoptive family had conservative leanings, too. Yet Decimus remained in Caesar's camp. It was probably early in 49 B.C. that Decimus issued coins celebrating his victories in Gaul, his loyalty, his sense of duty and spirit of unity—all propaganda themes of Caesar's in the civil war.

Excerpted from The Death of Caesar by Barry Strauss. Copyright © 2015 by Barry Strauss. Excerpted by permission of Simon & Schuster. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.