OK, this is intriguing!
According to the title it is the fifth Oath. So, do they fight until they reached the objective stated in their oath? Like "we, the members of the Red Army swear not to return while an enemy force is within an arrows flight of our borders"? Or did the former four Oaths lead to the Red Army being "forcibly dissolved"?
And if it's an Army, why are there only three, and all three of them elven archers (well, elves are obvious)?
Are they an army that consists only of Elven Archers, dancing around the enemy, confusing them with magic and unnaturally fast graceful movements?
Which makes this a great picture and well deserving the DD!