Georg Znaeym and Ulrich von Gradwitz are sworn enemies when "The Interlopers" by H.H. Munro (Saki) begins. Their feud is long-standing and goes back for several generations; the point of contention between them is a small strip of worthless land--both families think they own it.
Both of these characters are in the forest on this stormy night. They are prepared to hunt, but their prey is human. Each wants to kill the other; however, nature intervenes and instead the men are trapped by a fallen tree during a storm.
Things are uncomfortable for both of them at first and of course they share a few insults; but before long something changes. Ulrich ponders and then says,"
"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. Lying here to-night thinking I've come to think we've been rather fools; there are better things in life than getting the better of a boundary dispute. Neighbour, if you will help me to bury the old quarrel I--I will ask you to be my friend."
Georg does not answer at first, as of course it is a surprising thing for him to hear and consider. Then he begins to kind of laugh over what the people in town might thinks if the two men were suddenly friends instead of enemies. It is quite an amusing thought, and he finally he responds to Ulrich's offer of friendship this way:
"In all the countryside there are none that could hinder if we willed to make peace. I never thought to have wanted to do other than hate you all my life, but I think I have changed my mind about things too, this last half-hour. And you offered me your wineflask...Ulrich von Gradwitz, I will be your friend."
The key word in your question is "true," and it does seem that the men mean what they say. Neither of them speaks without thinking, and they are deliberate in both the offer and the acceptance. I find their conversion to friendship believable.