Second war against Veii
Not enough room
The inducement to the second war against Veii was the same as always: too many people in a too small area. The city of Veii was situated only 18 km from Rome, be it at the other side of the river Tiber. Closer by was Fidenae at a distance of only 8 km and like Rome at the left bank of the river.
It is amazing how two cities, separated by no more than two hours of march, had existed next to one another, for almost 300 years. Not peacefully though. Romulus himself had subdued Fidenae for the first time, this may be mythical, like the battle Numa Pompilius fought against Fidenae, but the first of the consuls P. Valerius Publicola had to fight a war in which Fidenae had also participated against Rome.
In fact Fidenae was more or less reduced to a Roman colony. They didn't like that and in 437 they decided to change camp and turned to Lars Tulumnius, king of Veii. When Rome sent envoy to find out why the Fidenaeians had changed camp, the envoys were murdered on Tulumnius' orders
In those days reason enough to start a war.
11 years of war
After the first bloody battle the senate appointed a dictator: Mam. Aemilius Mamercinus. Under his command the Romans won the next battle, but the war was far from over. This war would last for 11 years. Still, campaigns were fought during the summer time; the only time when it was interesting to plunder the fields of the enemy.
In the year 434 BC Q. Servilius was appointed dictator. When Roma was weakened by an epidemic, it was attacked again by Veii and Fidenae. The dictator led an all out attack on Fidenae and realizing he could not overrun the city nor was it very possible to besiege the town, he decided to dig a tunnel. He took the city by surprise.
Mars or Ares, god of war
MET New York
No obligation to help
Term of censor shortened
Aemilius who, according to Livius, didn't like long term offices very much, shortened the duration of the office of censor from 5 years to 18 months and next he resigned. He didn't make friends with that action.
In 426 bc 4 Military tribunes with consular power were elected. They decided to attack Veii again. Three of them marched towards Veii, but due to a complete lack of coordination, they were defeated. Rome in fear; the senate appointed Mam. Aemilius dictator. Evidently the Romans had not destroyed Fidenae nor led the people into slavery, because Fidenae took part in the battle that followed. Again Fidenae is conquered. This time the city was destroyed and lots of prisoners sold as slaves. Veii was granted a truce for 20 years.