Every battle in Valkyria Chronicles gets ranked, with letters from A to D - A being the highest and D being the lowest. A higher ranking will award you with more experience and money to improve and outfit your troops.
The rank you get is solely determined by the number of turns you finish the battle on. While you can always check during a battle what rank you'll get for finishing the battle on the current turn (by looking at your Objectives), there's no indication of the limit for an A rank, or a B rank et cetera. You'll only know that you missed the turn limit when you already dropped to a lower rank.

This guide is a compiled list of all the battle's turn limits to get each rank. This is an example of how it's displayed:


In this hypothetical battle, you will get an A rank as long as you finish the battle on turns 1, 2 or 3. If you finish on turns 4-6, you'll get a B rank and for turns 7-8 you will get a C rank.
Note that D rank is the lowest you can get, which means that the turn limit for getting a D is also the turn limit for the battle. If you pass the D rank limit, the battle ends - whether you win or lose in that case, depends on the battle conditions. Save for a few exceptions, the battle's turn limit is almost always 20 turns.

You will get one or two battles per story chapter. In the case that there are two battles in a chapter, i've marked them with -A and -B.

Reports are extra chapters centered around certain persons or topics that you can buy in-game from the reporter. Not all of them have battles. The ones that do are listed here.

You'll find these DLC class challenges when turning the page in the Skirmish tab in the game.

These are DLC battles that you reach by selecting "Extras" on the main menu (before loading a save game). They are separate from the main game and do not use your story progress or units at all.