Coincidences are indeed a thing.
It had already been two days since Kent led his legion and his Dragon Harem to evade the Hound Barracks and kill every last Hellhound. Not even one managed to escape.
Their loss was brutal, and as such, when the Hound King found out, he was so enraged that he nearly burned down his palace.
However, that anger was soon directed at the Lionkin. The reason being that every last Hellhound died, and they didn't know something that grim had happened.
A day after the attack, a unit of Hellhounds, who were scheduled to replace another unit, discovered the attack and immediately alerted their king.
The coincidence part was that a few hours after the Hellhounds became aware of this massacre, the Lions attacked one of their other barracks.
Perhaps, sometimes, the anger most people feel should be resolved first before battles.
