Eusebius of Caesarea

Joshua, the successor of Moses, calls the leader of the heavenly angels and archangels and of the supernal powers and as if he were the power and wisdom of the Father, entrusted with the second rank of sovereignty and rule over all, “prince of the host of the Lord,” although he saw him only in the form and shape of a man. At any rate, it is written: “And it came to pass, when Joshua was in the field of the city of Jericho, he lifted up his eyes, and saw a man standing over against him, holding a drawn sword, and he went to him and said: ‘Are you one of ours, or of our adversaries?’ And he said to him, ‘I am prince of the host of the Lord and I have now come.’ And Joshua fell on his face to the ground and said to him, ‘What does my Lord command to his servant?’ And the prince of the Lord said to Joshua, ‘Loose your shoe from off your feet, for the place on which you stand is a holy place.’ ” Here, too, you will perceive from the identity of words that this is no other than he who also spoke to Moses.

And as Joshua, the successor of Moses, was about to fight against the former possessors of Palestine, his enemies, foreign and most ungodly races, he rightly appears to him with a sword drawn and pointed against the enemy, showing by the vision that he himself is about to attack the ungodly with an unseen sword and with divine power, the fellow soldier and the fellow combatant of his people. Wherefore he gives himself the name of Chief and Captain of the Lord to suit the occasion. - "Proof of the Gospel 5.19"