I think it was because they had 2 protect their home too
<span>The obligations of serfs were to work for lords and knights. Serfs lives were much more difficult than that of a lord or knight. Serfs didn't have freedoms like the lords and knights. Knights would sometimes serve the lord as well but could also be the lord of a castle. Serfs didn't have that option.</span>
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If I wanted to get a better salary, my boss and I would have to bargain to figure out what is fair. A big example with this is in factories with working conditions. For example, wanting a certain amount of break time, or having drinks included with their work, etc. I don't know what they examples are, but this definition should help you out. If it doesn't, just comment what the examples are and I'll help figure out which one it is.
The Mexican American War heightened tensions over slavery in that there were many disagreements over whether the new territories won from Mexico should be free or slave territories. The Wilmot Proviso, created to solve the problem, ended up slitting parties on regional areas.
Good luck :)