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?
Notice the spies' timidity even at the beginning of their report, and they become increasingly fearful. If, because of God's promises in Exodus 23, they did not expect confrontation, why do they show so much trepidation? Even Joshua and Caleb expected confrontation. They most certainly did not understand that God's promises in Exodus 23 would be fulfilled without them having to lift so much as a finger to gain the land. They knew they would have to make war against the people of the land.
The underlying problem was that they did not trust that the warfare would be a cooperative effort. In effect, they believed that God could not do it. They did not trust that God would be with them, cooperating with them and fighting on their side against the common enemy, the people of the land. Joshua and Caleb knew there would be combat, but the difference was that they were confident that God would fight for Israel and against the Canaanites.
John W. Ritenbaugh
The Christian Fight (Part One)