Harold Miller created the topic: On Building a Nation in Shoftim
This dispatch to has the potential to be sensitive and / or politically charged. I don't mean it that way. I think Perek 3 P'sukim 1-4 are critical. I interpret as follows. It has two messages: One is a religious one (don't worship idols), and the other explains how to build a nation. The pasuk says specifically that B'nei Yisrael need to learn how to wage war. However, it could be interpreted more broadly. In other words, it is a long process to set up and build a new nation in a new land.
Those on the left and the right would interpret that to suit their own politics. (The Kahane Chai ppl would say, See we have to wage war against everyone, until every last enemy is vanquished. While those on the left would say, No, in modern times, diplomacy is the tool of choice, not war...)
Regardless of the politics, I would say that back then, war was one of the key metrics for the success of a nation. G-d is saying, I need to educate you, slowly, over time. Compare this with the beginning of Parshat B'shalach. G-d does not take them via the shorter route, because He is aware of the "educational" level of the nation. They're a newborn nation and not ready to wage war.
This process takes several hundred years before we finally achieve the sucess and stability of the Kingdom under David haMelech.
Perhaps there is a lesson in all this for the Modern State of Israel, which is only 60+ years old. (If you count going all the way back to Herzl and the first Olim, is only a little over a hundred years old.) I don't know if I should be heartened or discouraged.