what is Beah's first personal contact with the rebellion

Do you mean the government forces or the RUF?

RUF

In chapter 1, the local friends arrive home early with the news that school has been cancelled since Mogbwemo, Beah’s home sixteen miles away, has been attacked by rebels. One Mattru Jong friend, Gibrilla, states that the teachers believe Mattru Jong itself will be the rebels’ next target. Despite this possibility, many refugees from Mobwembo flee to Mattru Jong; therefore, Beah and his friends go to the nearby wharf to await the incoming people and look for their families among the refugees.