
The 22nd chapter of Joshua reads much like "The Hunt for Red October" -- well, except for the fact that it's about pre-Davidic Jewish tribal tensions instead of U.S. - Soviet Cold War tensions... and except for the fact that it involves swords and arrows instead of nuclear arsenals... and except for the fact that there is no double-agent high-level espionage involved... But really, other than those particular differences, the stories are almost exactly alike. :-)
The stories are alike because they both involve calamity hanging in the balance of understanding.
In the 22nd chapter of Joshua, the campaign to conquer the Promised Land has been completed. The Reubenites, Gadites, and the half-tribe of Manasseh (R, G, & ½M) proved themselves faithful in Israel's military mission. Even though their own territory had been secured years earlier, on the eastern bank of the Jordan River, they didn't skip out on their brothers in their time of need. They served well, so when the objectives were accomplished, they were sent back to Gilead with a blessing and a personal thank-you note from the hand of Joshua himself. The only word of hesitation or caution that was given upon their departure was this: "But be very careful to keep the commandment and the law that Moses the servant of the LORD gave you: to love the LORD your God, to walk in all his ways, to obey his commands, to hold fast to him and to serve him with all your heart and all your soul." R, G, & ½M readily agree to this advice, so they start walking back to Gilead with a spring in their step, a song on their lips, and hearts full of warmth, gratitude, and satisfaction in a job well done.
So what do they do when they first set foot in their newly-blessed territory? They make an altar. And why not? It was exactly what they had seen Joshua do when they first entered the Promised Land. It's the same kind of thing that happened right after the miraculous crossing of the Jordan (Joshua 4:9) and right after the Covenant was renewed on Mount Ebal, following the victories over Jericho and Ai (Joshua 8:30) -- not to mention all the other piles of rocks that were intended to serve as reminders to the people of Israel (Joshua 6:26, 7:26, 8:29, and 10:27). Rock altars were the tradition.
However, for whatever reason -- perhaps hyper-vigilance, hyper-legalism, seeds of distrust, "sibling rivalry," or just some unrecorded piece of misinformation that got out of control -- the other 9½ tribes of Israel automatically assume that R, G, & ½M are up to no good: that they're already abandoning the LORD and resorting to idol worship. As soon as they observe the altar being built, they prepare for war!
From the perspective of history (and limited-omniscient, third-person narration), we can see that both sides actually had honorable intentions. R, G, & ½M were doing everything they could think of to preserve their communal relationship with the LORD and make sure they wouldn't just drift away into idolatry. And likewise, the other 9½ tribes of Israel were just doing everything in their power to preserve the worship of the LORD in Israel and make sure that their kinsmen wouldn't just drift away into idolatry. The main problem was simply miscommunication! They misunderstood each other, and they miscommunicated their motives to each other, and thus they brought themselves to the brink of civil war -- over nothing but misunderstanding and miscommunication.
Fortunately, the 9½ tribes west of the Jordan had just enough wherewithal to send a delegation to R, G, & ½M to raise the question that had come up in their minds. Now, I don't think we can hold up the delegation's message as any kind of ideal for other such situations -- as it was ridiculously heavy with assumption and accusation, which is not typically the best way to diffuse tension -- but at least they went in with words before they went in with swords. And fortunately, R, G, & ½M were able to listen well to the other tribes' concerns and respond with important reassurances. The first words of response, in fact, were probably some of the most reassuring: "The Mighty One, God, the LORD! The Mighty One, God, the LORD! He knows! And let Israel know!" They weren't turning their backs on the LORD at all. He was actually the star witness to the trial of their motivations. The rest of their explanation must have been very reassuring, too; because in truth, R, G, & ½M's motives were exactly the opposite of what the other 9½ tribes had assumed. They were much more united than had been feared. So ultimately, the delegation from the western tribes of Israel were able to issue the order for their armies to stand down, and trust was restored in the Promised Land: "Today we know that the LORD is with us, because you have not acted unfaithfully toward the LORD in this matter. Now you have rescued the Israelites from the LORD's hand." Nuclear holocaust was averted. Peace was preserved. And trust between the various tribes of the newly-established Israel was restored.
To remember the whole incident, and the principles of unadulterated worship for which it stood, R, G, & ½M's altar remained on the eastern side of the Jordan. And the people on that side of the river gave it this name: "A Witness Between Us that the LORD is God."