The Jaredite Civil War
According to Ether, over 2 million men, plus their wives and children perished during the final civil war on just one side (Ether 15:2). It is difficult to comprehend, using modern warfare tactics of the 19th – 21st Centuries, how two armies can battle down to 30 people (Ether 9:12) before someone decides to end the battle.
The difference lies in war strategy and technology. Today, we can target specific people, however, when the leader falls, another takes his place. In the days of the Jaredites, the war ended with the death or capture of the king. The preferred methodology was capture. Consider how many sons imprisoned their fathers or vice versa, and kept them there until they died or were freed.