noun
battle picture scroll
A horizontal illustrated scroll (emaki) depicting a famous historical battle, often with narrative text.
この博物館には平安時代の合戦絵巻が展示されている。
This museum displays a battle picture scroll from the Heian period.
絵巻物 is the general term for picture scrolls; 合戦絵巻 specifically refers to those depicting battles.
Compound of 合戦 (battle) and 絵巻 (picture scroll).