A Mock Triumph
Contributed by David Verne
The emperor, Domitian, has always been jealous of the military glory won by his father and brother. Even though he believes in Augustus' advice to not expand the Empire further, he decides to embark on a military campaign of his own. On the pretense of conducting a census in Gaul, he gathers a couple legions, including transferring units from other commanders that needed them. He decides to pick a target that would be easy to defeat and launches an attack on the Chatti, a Germanic tribe that been allied with Rome for several years. After regrouping following the initial assault, the Chatti begin harassing Roman supply lines and launching guerrilla attacks, but the Roman numbers are too great. Domitian pushes the Roman frontier into the area of modern day Bavaria and begins the construction of forts and roads.
With winter approaching, Domitian decides that it would be best to gain a victory, so he declares a victory and leaves. In Rome, he celebrates a Triumph for his "victory" over the Chatti and gives himself the title Germanicus. Tacitus calls the whole thing a "mock Triumph" and claimed that Domitian dressed slaves from the marketplace in German clothing and had them grow beards to make it look like large amounts of prisoners had been captured. 
- Dando-Collins, Stephen (2010). Legions of Rome. St. Martin's Press.