義戦 is read as ぎせん (gisen) and means crusade.
ぎせん
gisen
せんじきょうさんしゅぎ
war communism (Russia, 1918-1921)
はんせんしゅぎ
pacifism
はんせんしゅぎしゃ
pacifist
ぎてい
brother-in-law (spouse's younger brother or younger sister's husband)
あに
brother-in-law (spouse's older brother or older sister's husband)
あね
sister-in-law (spouse's older sister or older brother's wife)
ぎまい
sister-in-law (spouse's younger sister or younger brother's wife)
ぎむ
duty
ぎり
in-law
ぎふ
father-in-law
ぎぼ
foster mother
ぎし
artificial tooth