The episode is praised for its emotional maturity. Critics note that while the title suggests a war of swords, the real "war" is the destruction of Ragnar's marriage.
“If you are going to have Rollo betray him in the very first episode... at least have some consequences of it. He should be dealing with the guilt... rather than dealing with his brother still being his nemesis.” Reddit · r/vikingstv · 12 years ago Vikings - Review of Season 2 Episode 1: Brother's War Brother's WarVikings : Season 2 Episode 1
Some reviewers feel the resolution of Rollo's betrayal was slightly "anti-climactic" or "forced," as the series used a "divine intervention" excuse through the Lawgiver to keep him in the story. The episode is praised for its emotional maturity
Back in Kattegat, Rollo's life is spared by the Lawgiver—later revealed to be because Ragnar bribed the official. at least have some consequences of it