The conflict between the Iron Fur and the sharp tooth pack didn't start and end in a single day. It has been going on for a long time. In that period of time, Sauron had been using some less-than-honorable tactics to weaken the sharp tooth tribe. They are tactics that is usually frowned upon.
He would ambush their warriors when they went out to hunt. He didn't attack them personally so that it wouldn't be considered bullying but he made the warriors of the iron pack attack those of the sharp tooth without any reason. They attacked and killed the paragons of the sharp tooth pack without being officially at war with them.
Those preemptive strikes caught the sharp tooth pack off guard. They couldn't defend themselves against the sudden attack. This way, Sauron reduced the manpower of the sharp tooth pack and also weakened their pack leader.
A paragon gets a boost based on the number of connections that they have. For Warrogs, Betas are at the bottom of the ladder, they don't get any boost. Alphas get a boost from the amount of Betas that they can subjugate and control while the Alpha of Alphas gets stronger the more people are in the pack.
It doesn't matter if they are nameless, Betas, or Alphas. They will strengthen the pack leader as long as they are part of the pack. This is how it is for other races too except that Paragons only awaken at the Mana entity stage. It is different for Warrogs because they have a method to forcefully awaken their divine ability. So to weaken a pack leader, you just have to use the method to weaken any paragon. Which is reducing the population under their control.
Warrogs are honorable to a certain degree. No one touches the Nameless. The nameless are the normal Warrogs. They haven't awakened their divine ability yet, so they don't have names. They are identified through scent and physical features. It is only when a Warrog awakens that they are given a name. A name has to come from a superior so it can come from an Alpha, the pack leader, a Shaman, or the totem pole.
Awakening as a warrior and getting a name is a glorious thing. But as long as you don't have a name, you won't be targeted by the conflicts of the hierarchy or between packs. It is, as they say, The Nameless Are Blameless. That means that Sauron had to target the warriors if it wanted to weaken the park leader of the sharp tooth pack. Even he is not as dishonorable as to attack the Nameless.
His shameless but logical tactics bore fruit. It was a sort of siege on the sharp tooth pack. They couldn't hunt without being attacked. The pack leader of the sharp tooth pack wasn't foolish. He recognized what was going on and he tried to make a full fight occur between both packs but Sauron wasn't willing to see that happen.
Sauron refused to have a full battle between both packs. The only choice the pack leader had was to either go and attack Sauron in the location of the iron fur pack or personally lead his warriors to hunt. Sauron will have to face him if he wants to attack his warriors.
The pack leader of the sharp tooth pack took the latter option. He led his warriors out to hunt. That was his preferred option because the iron fur pack is located up the mountain while his park is located at the foot of the mountain. He would be at a disadvantage in terrain if he attacked the iron fur pack.
The pack leader of the sharp tooth pack took his warrior out to hunt but Sauron wasn't stumped. He descended the mountain and attacked the valley where the sharp tooth pack was located. Sauron didn't kill or harm any nameless. He killed only the Paragons still in the settlement. The pack leader's pregnant mates like Ragnarok's mother Cuthalin were also present but Sauron didn't touch them either. He only killed the guards and warriors left in the valley.
Sauron played according to the rules but he was shameless about it. No one can say that he was dishonorable. He made sure to follow the rules of war between packs. He didn't touch the nameless.
But the pack leader of the sharp tooth pack didn't think so. A lot of his sons and new Paragons were killed that day. They were too young and weak to hunt. They still needed training before they could control their beast form properly so the pack leader left them back at the settlement where they should have been safe.
Ragnarok's father thought they would be safe. They ought to be safe in their own house but Sauron killed them. He killed them despite their young age because they were Paragons. Sauron had been killing the current generation of warriors before but that wasn't enough for him. He turned his attention to the future generation too. That was the straw that broke the camel's back.
The pack leader of the sharp tooth pack took his hungry and angry warriors on a crusade. He ascended the mountain and assaulted the iron fur pack. He wouldn't take no for an answer this time. He took the fight to them after being harassed for so long. It became a do-or-die affair. He wanted a fight even if it was a bad idea.
He was going to pillage and burn no matter what Sauron thought of it. So Sauron had to fight. They fought a bloody battle at the gate of the iron fur's pack. The sharp tooth pack was incensed with righteous anger while the iron fur had a larger number of warriors and most importantly, they were well-fed warriors The outcome of the fight was set in stone.
Sauron won the clash easily. He defeated the pack leader and chased the sharp tooth pack down the mountain. The defeated park leader was supposed to admit defeat but he refused. He didn't give the order to surrender and until he dies, his orders must be obeyed. He himself escaped so Sauron gave chase.