Purpose of the Spies in Yehoshua 2

Introduction

Why Send Spies?

Yehoshua 2 describes Yehoshua's dispatching of spies to Yericho, their near discovery by the king's officers, and their narrow escape with the aid of Rachav.   At first glance, it would seem that the stealth with which Yehoshua sent the spies confirms that their purpose was a covert military operation designed to discover the weak points in Yericho’s fortifications. However, if Yehoshua conquered Yericho through a Divine miracle in which the walls came tumbling down, why was such a mission necessary? Why risk lives for superfluous military intelligence?  Moreover, the text never describes any investigation of the city's ramparts, and, upon their return, the spies share no strategic information.  Was their mission aborted before accomplishing its goal, or did it have a different purpose to begin with?

Interactions with Rachav

The spies' implementation of their mission raises several questions as well:

• Red light district? Why, of all places, did the spies choose to go to a brothel to gather their information?¹ In addition, what did they hope to gain from spending the night there? Would it not have been more sensible to leave at dusk rather than risk being cornered and caught inside a city which locked its gates at night?
• Role of the scarlet cord – Why did the spies insist that Rachav hang a scarlet cord from her window in the wall? If the rope was meant merely to identify Rachav's house, this would be of little value to invading soldiers who would be approaching her house from inside, and not outside, the city.²  In addition, when the walls collapsed, what would remain of such a cord? 
• Condition of secrecy – Why were the spies concerned lest Rachav reveal their pact? After all, they had escaped regardless!³ Was it not she who would stand to lose as she admitted to betraying her nation and abetting the enemy?

Divine or Human Conquest?

Many of the above questions connect to a larger issue: what is the relationship between the description of the conquest of Yericho in Chapter 6 and the espionage mission of Chapter 2?  While Chapter 2 speaks of human preparations for conquest, Chapter 6 emphasizes Divine intervention. Details such as the scarlet cord seem forgotten, and the human efforts of Chapter 2 appear irrelevant in face of Hashem's miracles. How are we to understand the apparent inconsistency between the chapters?

¹ Not all agree that Rachav was a prostitute, though the common usage of the word "זוֹנָה" in Tanakh would support that definition. See JosephusAntiquities of the Jews 5:1:1About Josephus who claims that Rachav owned a motel, and Targum YonatanYehoshua 2:1About Targum Yonatan (Neviim) which renders "זוֹנָה" as פונדקאית, an Aramaic word usually used to denote an innkeeper.  Radak, however, notes that the Targum often employs פונדקאית when the original Hebrew reads "זוֹנָה", and he therefore maintains that the Targum merely intended to literally render "זוֹנָה" as a prostitute.

² Since the cord was hung on a window facing the exterior of the city (as clear from the fact that the spies escaped Yericho via the window), it would be out of sight of soldiers entering her house from inside the city.

³ See RadakYehoshua 2:14Yehoshua 6:5About R. David Kimchi who points out that it is illogical to assume that the oath was meant to prevent Rachav from revealing the spies since she had already covered for them before the king's men.