QUEST: the general was defeated

I got the quest in the initial phase of island development. I ignored it as simply I did not have a medipack at that low level stage.
Last week I finished "The fallen army" and I received a medipack as reward.
Since the "TGWD" quest has not been completed I used the medipack to recover my general on adventure quest hoping to finally close it.

Unfortunatelly it did not work, the quest is still valid....Why???

The only resonable explanation could be that the quest refers to the island fighting, not to adventures, but in such a case it is too late to complete it.

Is it a bug or quest fail?

This is a known bug, try contacting Support regarding this.