War debuts on HBO and HBO Max on Thursday, October 1, at 9 p.m. eastern/pacific. Archie Renaux ( Shadow and Bone ) plays Johnny Warren, the young lawyer drawn into the conflict. Phoebe Fox ( The Great ) and James McArdle (Sexy Beast) play Serena Byrne and Nicholas Taylor, partners in life and business at Taylor & Byrne. Justin Downing/Sky/HBO Archie Renaux as lawyer Johnny Warren. We will continue to update this post as we learn more about season one of War.