And: the transition word here should probably be stronger than And in English. It should indicate that what follows is a direct result of David’s order received in the letter. In Hebrew the verse actually begins with the same verbal expression that introduces verse 1, 2, and 14 and that is often translated “And it came to pass….” This seems to indicate that a new stage in the story has been reached.
Was besieging the city: this takes the reader back to the summary statement in verse 1. See also 1 Sam 11.1. However, some scholars feel that what was actually written here meant “having watched the city” (compare Anchor Bible and Anderson), since the Hebrew verb means “to watch” or “to guard.” That is, this would provide something of an explanation as to how Joab knew where to place Uriah in the battle. Contemporary English Version follows this interpretation, with “Joab had been carefully watching the city….” Traduction œcuménique de la Bible has a similar rendering. If this interpretation is followed, in some cases it may be more natural to rearrange the elements of this verse and say something like “Joab watched the city to see where the strongest fighters were. Then he put Uriah in that place.” Most versions, however, retain the idea of a siege. Since this city was last named in verse 1, Parola Del Signore: La Bibbia in Lingua Corrente makes the name explicit here, translating “Joab was besieging the city of Rabbah.”
Assigned: literally “gave.” In compliance with the orders of his commander in chief, Joab puts Uriah in a spot that would almost certainly result in his death. Some other verbs that may be used here are “placed” (Traduction œcuménique de la Bible and Bible en français courant) and “stationed” (New Jerusalem Bible, Revised English Bible, and New Jewish Publication Society’s Tanakh).
Where he knew there were valiant men: Joab knew where the Ammonite forces were strongest and where their best soldiers were deployed. This was to be the spot where Uriah would have to fight. In many languages it will be advisable to make it clear that the valiant men being talked about are enemy soldiers and not Israelites. On the expression valiant men see 1 Sam 31.12.
Quoted with permission from Omanson, Roger L. and Ellington, John E. A Handbook on the First and Second Books of Samuel, Volume 2. (UBS Helps for Translators). New York: UBS, 2001. For this and other handbooks for translators see here .