No Path through Fire

Bring 4 Barrels of Explosives to the obstruction near Snake Waterfalls.

All right, listen up. Open your map and look here. This blotch in the center of the archipelago, crammed with miles and miles of rotting marches, is called the Windy Hills. What, don't feel like visiting? Well, too bad, 'cause you'll have to. For the moment it belongs to the white wings. They are backed by the League, and that means we'll be fighting for this worthless swampland as if it were a mine gushing meteorite! The brass has decided to help the red wings take over the marshes. An assault squadron has already been dispatched. They found a scrap of dry land, dug in and are now waiting for reinforcements... Except we can't send any! The League got wind of the attack and sabotaged our plans - they broke the lift and blocked the path. Now there's no way to get up there without wings.
But that's OK, 'cause if there's one thing they teach at the military command school is that any problem can be solved with enough explosives! And that we have plenty of... Well... We used to, at least.
Thing is, our brave boys were already carrying a load of explosives up here, but they landed in an anarchist ambush. We rushed to the rescue and did what we could, but it was too late... those reds that managed to survive bolted from the scene. After dropping all their loads, naturally. Luckily, the anarchists didn't have the chance to claim the spoils, so all those explosives are still in those bushes somewhere. I sent some goblins to look for them, but they are useless...
Maybe you'll have better luck? There were ten barrels in all. If you see any - grab it and bring it here!

If we don't recover enough explosives, we'll just have to do what Nezeb taught us - clear the way head on. As long as it's not my head!

One, two, three... Hey, we are four barrels short! I guess the anarchists grabbed 'em. What are we to do now?