The novel romanticized war, portraying the brutal battlefield as full of heroism.

romanticized 是动词 romanticize 的过去式形式。romanticize 由名词 romance（浪漫）加上动词后缀 -ize 构成，意思是"使...浪漫化、美化"。这里指将战争这种残酷的事情描绘得过于理想化和美好。