"I will be with you" is one of the great promises of God to his people, and of course means that close proximity, that he will be their God, and they will be his people, that he'll be with them, never leaving them, never forsaking them, that he'll be working for them. Oftentimes, I think when we hear that, what we're drawn to is the comfort that, even in the face of our sins and our struggles, God will remain steadfast, even when we're not. But in this particular context as God's people were getting ready to take possession of the Promised Land and go up against the Canaanite people — a strong and powerful people characterized by deep generational sin, a group of people that would have been terrifying to many outside that land as they looked in upon it — what God is really promising is that he won't only be with them, be faithful and steadfast for them, but that he'll fight for them, and he'll fight with them. And, of course, we see that in just a couple of chapters as the angel of the Lord appears to Joshua and reminds him that this is not purely an earthly battle between Joshua and the armies of Israel, it's the Lord of Hosts who is fighting with them and for them and is ultimately going to determine their success. So, it's meant to be a wonderful reassurance in many ways, but a chief way in which God is reassuring his people in the book of Joshua is that he will fight for them, and in fact, has been fighting for them.