Crassus was elected praetor in 73 BC and pursued the
cursus honorum. During the
Third Servile War, or Spartacus' revolt (73–71 BC), Crassus offered to equip, train, and lead new troops at his own expense, after several legions had been defeated and their commanders killed in battle. Crassus was sent into battle against Spartacus by the Senate. At first, he had trouble both in anticipating Spartacus' moves and in inspiring his army to strengthen their morale. When a segment of his army fled from battle, abandoning their weapons, Crassus revived the ancient practice of
decimation – i.e. executing one out of every ten men, with the victims selected by drawing lots.
Plutarch reports that "many things horrible and dreadful to see" occurred during the infliction of punishment, which was witnessed by the rest of Crassus' army. Nevertheless, according to
Appian, the troops' fighting spirit improved dramatically thereafter, since Crassus had demonstrated that "he was more dangerous to them than the enemy." Afterwards, when Spartacus retreated to the
Bruttium peninsula in the southwest of Italy, Crassus tried to pen up the slave armies by building a ditch and a rampart across the peninsula of Rhegium in Bruttium, "from sea to sea." Despite this remarkable feat, Spartacus and part of his army still managed to break out. On the night of a heavy snowstorm, they sneaked through Crassus' lines and made a bridge of dirt and tree branches over the ditch, thus escaping. Some time later, when the Roman armies led by Pompey and Varro Lucullus were recalled to Italy in support of Crassus, Spartacus decided to fight rather than find himself and his followers trapped between three armies, two of them returning from overseas action. In this last battle, the
battle of the Silarius river, Crassus gained a decisive victory, and captured six thousand slaves alive. During the fighting, Spartacus attempted to personally kill Crassus, slaughtering his way toward the general's position, but he succeeded only in killing two of the centurions guarding Crassus. Spartacus himself is believed to have been killed in the battle, although his body was never recovered. The six thousand captured slaves were
crucified along the
Via Appia by Crassus' orders. At his command, their bodies were not taken down afterwards, but remained rotting along Rome's principal route to the south. This was intended as an object lesson to anyone especially slaves who might think of rebelling against Roman citizens and slave-owners. Crassus effectively ended the Third Servile War in 71 BC. In Plutarch's account, Crassus "had written to the Senate that they must summon Lucullus from Thrace and Pompey from Spain, but he was sorry now that he had done so, and was eager to bring the war to an end before those generals came. He knew that the success would be ascribed to the one who came up with assistance, and not to himself." He decided to attack a splinter group of rebels, and after this, Spartacus withdrew to the mountains. Pompey had arrived from Hispania with his veterans and was sent to provide reinforcements. Crassus hurried to seek the final battle, which he won. Pompey arrived in time to deal with the disorganized and defeated fugitives, writing to the Senate that "indeed, Crassus had conquered the slaves, but that he himself had extirpated the war." According to Plutarch, "Crassus, for all his self-approval, did not venture to ask for the major triumph, and it was thought ignoble and mean in him to celebrate even the minor triumph on foot, called the ovation," nor did he wish to be honored for subduing slaves. In Plutarch's account, Pompey was asked to stand for the consulship. Crassus wanted to become his colleague and asked Pompey for his assistance. As said in the
Life of Crassus, "Pompey received his request gladly (for he was desirous of having Crassus, in some way or other, always in debt to him for some favor), eagerly promoted his candidature, and finally said in a speech to the assembly that he should be no less grateful to them for the colleague than for the office which he desired." In office, they did not remain friendly. They "differed on almost every measure, and by their contentiousness, rendered their consulship barren politically and without achievement." Crassus displayed his wealth by realizing public sacrifices to Hercules, entertaining the populace at 10,000 tables and distributing sufficient grain to last each family three months, an act that had the additional ends of performing a previously made religious vow of a tithe to the demigod
Hercules and also to gain support among the members of the popular party. In Appian's account, when Crassus ended the rebellion, there was a contention over honors between him and Pompey. Neither men dismissed their armies, with both being candidates for the consulship. Crassus had been praetor as the law of Sulla required. Pompey had been neither praetor nor quaestor, and was only 34 years old, but he had promised the plebeian tribunes to restore much of their power, that had been taken away by Sulla's constitutional reforms. Even when they were both chosen consuls, they did not dismiss their armies stationed near the city. Pompey said that he was awaiting the return of Metellus for his Spanish triumph; Crassus said that Pompey ought to dismiss his army first. In the end, Crassus yielded first, offering Pompey his hand. ==First Triumvirate alliance with Pompey and Caesar==