Violence is not a necessary condition of freedom. Although Hobbes, in his Leviathan, argues that a strong central state is necessary to prevent humans from acting according to their natural inclinations towards violence and brutality, in the 21st century, many of the nations with the greatest amount of freedom have the least violence. In fact, on could say that perhaps our most important form of freedom is freedom from violence, because we are not in any way free if our acts are constrained by fear of violence. One might also argue that their is no sich thing as absolute freedom (we are all constrained by a variety of physical, mental, and social limits) but instead that there are various types of freedoms, measured on relative scales. The most violent countries are often the most oppressive dictatorships.
Actual violence is not a necessary condition of freedom. However, the potential for violence is. When we have free will, we have the potential to do anything. We have the potential to do good and to do bad. As human beings, we are clearly prone to being violent when we have freedom. However, true freedom involves the ability to choose whether to be violent. If violence were a necessary condition, we would not truly be free because we would be compelled to be violent. Free will means having the capacity to do violence, but it also means having the capacity to refrain from violence. Therefore, violence is not a necessary condition of freedom.