Here we learn what happened to Merry and Pippin,

neatly matching the previous chapter in which their three friends are following.

Where we saw them making deductions about events the two hobbits see and sometimes cause.

From this viewpoint, we learn that there are three bands of Orcs.

At least two of them trusted each other enough to join in the attack on the Fellowship.

These are:

Orcs of Isengard, led by Uglúk. They are large, brave, and equipped like human warriors.

Orcs of Mordor, led by Grishnákh. Also large, but misshapen and much less like humans.

Orcs of Moria. No leader is mentioned.  They are small, and less resistant to daylight.

Only the first two are Uruk-Hai.