What the Bible says about Israel's Rejection of God's Lead
(From Forerunner Commentary)
After the census (Numbers 1), Israel, organized into armies, traveled the rest of the distance to the border of the Promised Land. Scouts spied out the land, and the majority gave a negative report. However, Caleb's response was positive: “Let us go up at once and take possession, for we are well able to overcome it” (Numbers 13:30).
Both Caleb and Joshua knew that with God on their side, they would be victorious in the battle. These righteous men understood God's intent for the clearing of the land to be a cooperative effort between God and Israel. Both parties would fight, and God's side would prevail. Of course, it did not turn out that way. Israel refused to follow God's lead in going to war, and as a consequence they had to wander for 38 years.
David C. Grabbe
Why Did God Command Israel to Go to War?