new and confused about this battle

[Gateway103]

Another possibility (besides a bug) is that you were attacked in provinces where you have substantial Province Defense, and/or your mages are fond of creature summoning, or similar effects.

The 37/38 killed only refer to mobile troops. By mobile I mean the troops you recruited in fortresses (and sometimes through events) or summoned via rituals, and are movable when assigned to commanders.

The latter number (38) refers to the number of mobile troops you had at the beginning of the battle, not the total number of troops (which may include mobile troops + Provincial Defense + in-battle unit acuisition via summoning, charming/enslaving/seducing, etc.) The former number (37), however, refers to the number of mobile troops you have at the end of the battle, compare to the starting value. This is why sometimes you get -x kills in report, when you "acquire" enemy units into service in combat.

As you can see, you may have say 20 Provincial Defense units in the combat, so at the onset of battle it looked like you got 68 troops. And at the end of the battle, 37 of your mobile troops are killed, with whatever number of PD, let's say 10. So from your perspective, you seemed to lose only 47/68 = 69%, rather than 37/38 = 97%.

Similarly, if your mages summoned creatures during combat, it may looked like you got more troops than 38, and perhaps not losing as many as 37/38 would suggest.

Hopefully this is clear... I got to stop writing Posts when feeling this sleepy... probably not making much sense...

-Gateway103