When he heard that the orcs were planning to invade Azeroth, Terenas formed an alliance between the other nations to fight off the orcs. The king also asked the elves and dwarves to help too. During the Second War, the forces of Lordaeron fought the orcs which ended in Lordaeron's favor. The warchief Orgrim Doomhammer was captured and became Terenas' prisoner. Doomhammer's imprisonment was not long as he was able to escape eventually.
Terenas became worried over his alliance as Gilneas, Quel'Thalas, and Stromgarde left. Arthas later became a paladin of the Silver Hand during the Third War. A prophet came to warn Terenas of trouble in Kalimdor but Terenas considered him insane and refused to listen to him. Prince Arthas returned from his journey into Northrend where Terenas held a celebration for his return. But the king didn't know about his son's now evil nature and was stabbed by him.