to the rebels and their cause against the Romans.

The wording of your question is interesting because Rosh doesn’t just want “a slave,” instead he wants only “this slave.” Why? Because the slave to be named “Samson” later is not typical. How do we know it is important to Rosh? Look at the exchange between Ebol (another member of the rebel group) and Daniel:

“Easy. No guard to speak of. All we’re to take is one slave.”

“No money?”

“Not a thing but the slave. A black fellow, big as an ox. Rosh spotted him yesterday when they stopped at Merom. Too good to waste on the galleys, Rosh says.”

This exchange tells the reader a lot. Specifically, it tells us that Rosh thinks that Samson is “too good to waste on the galleys.” Too good to kill, in other words. What is more important is what is implied here. If Samson is “big as an ox,” then Rosh most likely wants this “too good” slave to be of use the rebels in regards to physical labor. This is exactly what happens. What we don’t know at this time is that Samson is a mute (in that he doesn’t talk at all).

After Samson is taken from the packtrain we learn about Daniel’s new doubts about Rosh’s choice:

There was power there, all right. Those huge arms could crack the ribs of a man as easily as a child could snap a twig. But the broad face with the livid scar showed no sign of intelligence, only an animal wariness that would mark the time to strike.

Again, it is implied here, but who would Rosh want to have their ribs broken? The Romans, of course. Thus, the true usage of Samson becomes known indirectly. When Samson is finally brought to Rosh, the leader of the rebels is happy at his new recruit (although a bit unnerved that Samson won’t speak at all). The men begin to grumble in worry that Samson might turn on them in the night and kill them if Samson doesn’t understand whose side he’s on. Finally, Rosh hits the nail on the head:

We took him for his muscles, not his tongue. He’ll prove his worth soon enough.

This shows that Rosh is always promising that the final uprising against the Romans is right around the corner. Samson was chosen for power in that skirmish.

In conclusion, Rosh wants this particular slave he names “Samson” because of his strength (hopefully in fighting the Romans). What is interesting is what actually happens is that Daniel ends up getting a confidante for life. Daniel, as the blacksmith of the group, uses his prowess to set Samson free of his chains. This act of mercy and kindness and freedom bonds the two together (or perhaps I should say bonds Samson to Daniel). It takes a while for Daniel to warm up to Samson, but eventually Samson saves Daniel’s life, and Daniel will never forget that act just as Samson will never forget his freedom. I’m afraid it is Rosh, by the end of the book, who has chosen the wrong methods for success. Instead of war, the character of Jesus teaches us in The Bronze Bow that it is mercy and kindness and compassion that are key, not war.

Due to his size and capacity to be physically useful to the band of Zealots, Rosh thinks that Samson (the slave) would prove a valuable addition to his arsenal of manpower.Indeed, as time progresses, Samson would prove his worth by aiding in the completion of tasks previously a challenge for the group.

Joel's eyes met his in a brief salute, and between the two boys, something flashed, a wordless exchange that was both a farewell and a beginning.

The two young men bid farewell to each other, but the parting will only be temporary. The author has foreshadowed Joel's future role in the Zealot mission by intimating that this farewell is only the beginning of more interaction between Daniel and Joel. Joel's earlier assertion to Daniel that he wants to join Rosh's group and his subsequent brief interview before Rosh tells us that we will be seeing more of Joel's character and that he will play a central part in the story's plot.

As for whether Daniel's tactic of caring for the slave proves a good way to get Rosh's attention, we know that Daniel initially thought it was. After the ambush, Daniel claims responsibility for the slave's welfare when no one else wants to step up to the job. Daniel does this partly because he feels jealous of the attention Rosh appears to show Joel, despite the latter not having performed any particularly impressive feat. At least, that's what Daniel concludes about Joel's awkward attempt to help during the ambush.

Daniel is soon to regret taking charge of Samson because Rosh orders him to file off Samson's chains that very night. Daniel thinks that he has been given the physically taxing job only because of his training as a blacksmith. As for Rosh, the author portrays this character as a man who solely concerns himself with objectives and outcomes, as pertaining to the Zealot mission. As such, the men who follow him are merely physical tools he will use to attain both rudimentary and far-reaching goals in the mission to expel all Romans from Israel. While Daniel may have initially thought that taking charge of the slave and seeing to his needs would impress Rosh, it is doubtful whether the leader would care to agree.