It's impressive to be wrong about every single point made. The Horde and Alliance were at peace before and during the Broken Shore, discounting Ashran as a skirmish between nobodies. After the Broken Shore and the Alliance intelligence, run by a dreadlord at the time who was trying to sow conflict between the factions, the first attack to take place is by Alliance initiative when Genn and Rogers use an airship to bomb the Forsaken fleet while they're heading to Stormheim to assassinate the Horde's head of state. Afterwards, the Alliance and the Horde have no involvement in the plot until Silithus, there's no implication at all that peace settled.
In fact, Anduin explicitly states that the Gathering is a) not a peace offer or a peace summit and b) that this isn't a ceasefire. You can't have a ceasefire if there's no war. The Alliance and Horde are in a defacto cold war since the Broken Shore, which turns into a hot one with the War of Thorns. There are no joint events in the book to speak of, short of both Anduin and Sylvanas sending guys to heal the wound and the Gathering, which was already covered and had fuck all to do with the factions and everything to do with the Forsaken.
Saurfang was the brain behind the entire invasion and completely agreed with Sylvanas' sell for the War of Thorns, predicated on Genn trying to assassinate her in Stormheim. When he unveiled this plan to the giant Horde army he had, they were 100% on board. Saurfang has no legs to stand on in terms of whether they should have gone to war or not, and barely any claim on how it should be conducted given his sparing of Malfurion.Saurfang saw the truth behind this sham. His rebellion will put the Horde back on the right course.