Well, of course Buddhism has a violent side.
Nowadays, Buddhism is, whether directly or indirectly, one of the contributing factors in some of the world's major ethnic conflicts. It plays a direct role in forming the "cleavage lines," sharpening differences ethnic groups... For example, Sinhalese and the Tamils in Sri Lanka. One of the major factors that initially sparked the escalation of the conflict between the Buddhist majority and minority Muslim minorities, was the fact that Buddhism was used as a political tool to enforce the dominance of the Buddhist Bamar ethnic group. By enstating Buddhism as the only official state religion in Myanmar, you effectively negate the needs or demands of any other ethnic group that doesn't participate in that religion. There is also tons of rhetoric using Buddhism such as the duty of people to "protect the religion," etc.
Historically speaking, though, Buddhism has had a huge dose of violence and you could literally find hundreds of examples of Buddhist violence in history. You only have to think of the Sohei "warrior monks" of Heian Japan for a good example. These monks' primary function was to keep on the look out and charge out at anyone approaching their monastary from rival sects or political groups.
It's just a fact that Buddhism has a violent side. Buddhists, after all, are humans just like the members of any other religion. The religion clearly doesn't call for it, just as it's difficult to justify the Crusades with the Bible. Nowadays people speak of Buddhism as if it was the last religion on earth not have have become embroiled in politics, violence and war. But that's just looking at the world through rose colored glasses.http://en.wikipedia.org/wiki/Buddhism_and_violence