For the Future of Hyrule
The quest is unlocked after completing The Great Plateau scenario.
"From the very moment he learned of the Volunteer Army, King Rhoam has been eager for a chance to train with the fledgling militia. Get some supplies to ensure his training is effective."
"Swinging his claymore with the soldiers, the king refined his two-handed sword technique! His Majesty looked forward to forging a bright future with the Volunteer Army."
- King Rhoam: Bonus Combo