Here is the full list of all 49 Isonzo achievements.
The base game contains 45 achievements, and there are 3 DLC packs containing 4 achievements.
During the Ascent seasonal game mode, kill someone with a rock
Complete a "White War" offensive, participating in each battle
Complete a "German Intervention" offensive, participating in each battle
Complete a "Solstice" offensive, participating in each battle