After the death of Moses, the chief power passed into the hands of Joshua the son of Nun, for Moses had appointed him his successor, being a man very like himself in the good qualities which he displayed. Now, at the commencement of his rule, he sent messengers through the camp to instruct the people to make ready supplies of grain, and announces that they should march on the third day. But the river Jordan, a very powerful stream, hindered their crossing, because they did not have a supply of vessels for the occasion, and the stream could not be crossed by fords, as it was then rushing on in full flood.
He, therefore, orders the ark to be carried forward by the priests, and that they should take their stand against the current of the river. On this being done, Jordan is said to have been divided, and thus the army was led over on dry ground. There was in these places a town called Jericho, fortified with very strong walls, and not easy to be taken, either by storm or blockade. But Joshua, putting his trust in God, did not attack the city either by arms or force; he simply ordered the ark of God to be carried round the walls, while the priests walked before the ark, and sounded trumpets.
But when the ark had been carried round seven times, the walls and the towers fell; and the city was plundered and burnt. Then Joshua is said to have addressed the Lord, and to have called down a curse upon any one who should attempt to restore the town which had thus by divine help been demolished. Next, the army was led against Geth, and an ambuscade having been placed behind the city, Joshua, pretending fear, fled before the enemy. On seeing this, those who were in the town, opening the gates, began to press upon the enemy giving way. Thus, the men who were in ambush took the city, and all the inhabitants were slain, without one escaping: the king also was taken, and suffered capital punishment.
Source: Sacred History (New Advent)