As jacoblambuk says - pen all the males very closely, preferably in a 4'x4' pen overnight. I'm not sure how many males you have, but they need to have no room to take a run-up. Putting them in adjacent paddocks will simply infuriate them but will give them no chance to sort themselves out.
The new tup was simply establishing himself in the new group as the leader. The ram lambs would have established their own pecking order already, so for the new shearling it's essential that he dominates them to be boss. The fighting doesn't usually go on for long but can be scary to watch. They don't usually kill each other, especially when they are of different ages and sizes, as the younger ones usually back down quickly. There is always some tussling when something changes, as after shearing, or when the stock tup returns from tupping, but it all settles down.