One of the signs of MaShiach is he will fight the Wars of HaShem. Rabbi Yaron Reuven brings a Chiddush on the obligation to fight the wars of HaShem from the Book of Judges. After the war against Sisera, Barak cursed Meroz for not coming to join the fight. The Sages explain that from here we learn that anyone that doesn't defend the honor of HaShem and speak out against wicked people when they have the opportunity is cursed.