According to this thread on reddit
the game saves anytime you quit to the main menu while not in combat or conversation. It also saves at chapter changes and while resting in camp
the game autosaves whenever you are in closer-travel mode (side-view of the caravan, with small sprites, e.g. Camp/Village/Town/Godstone)(world-travel mode is also a side-view of the caravan, but sprites are tiny) and in a few other specific locations.
In the case of Chapter 3, the game will surely autosave when you reach the Tower, but I'm not sure if there's other save locations. This means that you'll probably have to go through all the Ridgehorn battles in-a-row.
and according to this steam thread
the game autosaves on checkpoints. The game also generates a single "Resume" save-lost when you quit anytime during a so-called close travel scene, e.g. when in Camp or in a town/village/godstone. It does not save if you quit in the middle of a battle or a dialogue.
Further info on saving that occurs during checkpoints can be found here
The game auto-saves everytime you go into Camp, or into a Village/Town where there's a building to click on (e.g. Rest, Market, Leave etc).
Apart from that "active" save-slot, there's also several save-slots automatically generated each time you meet an important story-checkpoint (e.g. a major city, a godstone, a chapter-start etc). Those "checkpoint" save-slots are overwritten each time you visit the specific locaton anew (e.g. on a next playthrough), and you can reload them anytime you like.