Finishing Up combat
The rest of the combat chapter exists solely in the DMG, and consists of various special circumstances under which groups of PCs may be required to fight. It starts off with a discussion of siege weapons. These weapons aren't to be used against PCs and thus it does not give any damage codes for "giant freakin' boulder launched by a catapult," which I believe they intend to be covered by "inescapable death" or possibly with saving throws.
The next section is Mounted combat, which covers things such as mounts panicking, fighting from horseback, and dismounting/being dismounted. Not too much unusual, thought he rules for a panicked mount rely on optional rules(and a proficiency that doesn't exist).
You then have two versions of flying rules. BOTH are optional, and thus not core. This results in the fact that there are no actual flying rules for 2nd edition in a nothing but core game. The MM seems to assumed use of one or a combination of both rules systems.
The last part in the discussion of combat is Underwater breathing. I know most DMs and players hated using these rules. The most important rules for this are the vision and weapon penalties. As well as knowledge that flame spells don't work, while electrical spells all act like fireballs. So this is just one more good example of when NOT to cast Shocking Grasp.
Up next: Chapter 10: Treasure and Magical Items! We're done with combat! Woohoo!