At the beginning of "The Interlopers," we are told that there is a great enmity between the two protagonists, Ulrich and Georg. They hate one another and want to kill one another. It so happens that they come face-to face in the woods, each man with his gun pointed at the other. However, before either of them can shoot, a huge tree collapses onto them, trapping them both beneath the weight of its branches.

In the climax of the story, trapped beneath the huge fallen tree, Ulrich and Georg eventually reconcile. As they wait to be rescued, they allow themselves to contemplate "the wonderful changes that this dramatic reconciliation [will] bring about." However, Ulrich and Georg see "figures coming through the woods," towards where they are trapped. At first they think that the figures are perhaps the friends of one or the other of them, but then Ulrich sees what the figures really are. He laughs "the idiotic chattering laugh of a man unstrung with hideous fear" and utters the word, "Wolves."

This is a tragically ironic climax. Ulrich and Georg have for so long been consumed with an utterly destructive hate for one another, and yet when they finally reconcile and look forward to a better, more peaceful future, that future is cruelly taken from them, or at least seems very much like it will be taken from them, by the wolves. The climax is also a cliff-hanger. We leave the story with the wolves approaching Ulrich and Georg, but we don't see the wolves attack. An optimistic reader might hold on to the faint hope that Ulrich and Georg somehow escape.

Since there are two major conflicts, an argument can be made that there are two climactic moments. With the conflict of Man vs. Man, the climax comes when the two enemies, Ulrich von Gradwitz and Georg Znaeym, reconcile their differences. Then, once they are friends, they are yet engaged in another conflict: Man vs. Nature.

The climax of this conflict comes as the two men shout to beckon what they think are their hunters. Moreover, this climax is really the point of highest intensity in the story, and it comes near the end as is customary for climaxes.

Having reconciled their differences, the two men, enemies who have begun a friendship, decide that since the wind has lessened, they may be able to reach the hearing of their hunters who are patrolling the wooded strip of land. Ulrich suggests,

"Let's shout for help...in this lull our voices may carry a little way."

Georg observes that it will be almost impossible for their voices to carry through the dense forest with its trees and undergrowth: "...but we can try. Together then." And the two men raise their voices together. Soon, Ulrich tells Georg that he has heard something; however, Georg replies that he has heard nothing. After a silence of a few moments, Ulrich cries out joyfully, "I can see figures coming through the woods."

Together both men summon the figures by shouting as loud as they can. After a few moments, Ulrich cries out in joy,

"They hear us! They've stopped. Now they see us. They're running down the hill toward us."

"Who are they?" asks Georg, who hopes his men are on the way so that he can be the first one to extend courtesies to his new friend. But, Ulrich would rather that he did not recognize them, nor have called them: "Wolves."

The climax of “The Interlopers” is the point where Ulrich and Georg agree to work together.

The climax is the moment of greatest emotional intensity, or the turning point in the story.  It can occur anywhere, but will usually be near the end.  It is the point where the problem is solved or changes, and there is a new problem or no problem.

At the beginning of the story, the two men are enemies.

The two enemies stood glaring at one another for a long silent moment. Each had a rifle in his hand, each had hate in his heart and murder uppermost in his mind.

Yet when a tree falls on them, they decide to change their minds.  They are going to stop being enemies.  They realize the pointlessness of it.

We have quarrelled like devils all our lives over this stupid strip of forest, where the trees can't even stand upright in a breath of wind.

At this point, the story has changed.  The men go from being two men who are trying to kill each other to two men who have decided to not be enemies anymore.  At this point, the men agree to work together and call for help—good thing to, because wolves are coming.

The climax of the story is when Ulrich Von Gradwitz and Georg Znaeym meet face to face in the forest. A bit of context is important to set up the scene. 

Ulrich and Georg are enemies. Their families have been feuding over a stretch of land. When Ulrich is scouting with a group of his men to make sure that Georg and his men are not poaching, he comes face to face with Georg. This is the moment that Ulrich was waiting for. 

When the men see each other, the climax rises. What will they do? What will happen? Unbeknownst to all, there is a wind that knocks down a tree, which falls on both men. They, therefore, are pinned down, helpless. This is the climax of the story. 

As the men face each other in silence, they finally come to their senses. Ulrich offers wine to Georg, and both men realize that their feud is foolish. They, therefore, become friends and want to move forward. This is the resolution. All seems well, but when they hear footsteps approaching, they realize that these footsteps are not men but wolves. Hence, the story ends with a twist.