Why do you assume that Joshua's mindset was one of doubt and fear? Scriptural defense? Isn't Joshua the one who went onto the battlefield and faced the angel alone challenging his allegiance? Doesn't sound like doubt or fear.

When Joshua was by Jericho, he lifted up his eyes and looked, and behold, a man was standing before him with his drawn sword in his hand. And Joshua went to him and said to him, “Are you for us, or for our adversaries?”

Joshua 5:13 When Joshua was by Jericho, he lifted up his eyes and looked, and behold, a man was standing before him with his drawn sword in his hand. And Joshua went to him and said to him, “Are you for us, or for our adversaries?”