Humans are social creatures. We have a need to involve others in our lives, to spread ideas and work with our fellow man. Sometimes this social requirement works in our favour – we worked together to get to the moon, and we invented pie! But occasionally our need for social interaction means we come across someone that we wish would just... catch on fire.
There is sometimes a logical origin to a feud. When two people of differing beliefs are in a similar position, it's entirely understandable that they may butt heads. This tends to be why organised sports produces the best rivalries, each side wants to win and by winning can prove their superiority. Outside of sports, though, people have found some ridiculous reasons to battle, both physically and mentally.
Many of the following entries need a lot of historical context to truly understand why these people fought, and unfortunately this context is sometimes lost within the fog of time or hearsay. It's difficult to say who was right and who was wrong - this is subjective - but what is fair to say is that the inevitable feud that followed, although predicated on logic, became something far more venomous as time went on.
There are two sides to every argument and it's up to the judge to decide who wins; in this context, you are the judge.
10. Cato Vs. Caesar: Keep The Rome Fires Burning
Cato and Caesar's relationship was already pretty strained by the time Julius became consul (the highest office in Rome). He was forced to choose between a parade in his honour and running for consul, because Cato filibustered the senate so he couldn't do both.
Caesar's time in the senate was marked by a large amount of legislation used to provide land and wealth to the poor, Cato attempted to block most of these acts as he viewed them as politically motivated and an attempt to curry favour amongst the people.
Cato took any opportunity he could to talk about how Caesar was plotting to take over and destroy the republic; and he was kind of right.
When Caesar marched his troops across the Rubicon, eyes fell on Cato who promptly informed the men who had ignored his warnings: 'called it' (or something to that effect).
In 46 BC Cato, in Africa, his troops destroyed from the drawn out Roman Civil War and without hope of defeating Caesar, was offered a pardon by the new tyrant (at the time, the word had fewer terrible connotations).
Rather than admitting Caesar's claim as the one true leader of Rome, Cato committed suicide via a dagger to the stomach. Caesar would eventually get his by means of a dagger too... or several daggers rather.