From the preview:
After following its cast of characters through a web of events that spanned the galaxy, Rogue One: A Star Wars Story built toward its climactic battle on and above the planet Scarif.
With nothing less than the fate of the entire galaxy at stake, Rebels and Imperials fought in the jungles, in the heavy guarded Citadel Tower, in the skies, and even in space. It was the first major battle of the Galactic Civil War between the Galactic Empire and the fledgling Rebel Alliance, and were it not for the Rebel victory, the Rebellion—and the galaxy's hopes for freedom—would have been swiftly eradicated.
But the battle almost didn't take place. At an earlier council meeting, Rebel leaders voted against confronting the Imperials at Scarif. It was only because a few brave individuals disobeyed the council's wishes and risked their lives—sacrificed their lives—that the Rebel Alliance ended up with the Death Star plans and survived to continue in its fight.
Likewise, in Star Wars™: Rebellion, you won't find your Rebel Alliance eager to engage the evil Galactic Empire in military engagements. The Empire is far stronger. Its tools of war are far more devastating. But there are times that key individuals and key engagements can change the course of history.
In the long run, war is inevitable. Combat is inevitable. And with the new units and advanced rules from the Rise of the Empire expansion, that combat is far more nuanced, dynamic, cinematic, and dramatic than ever.