Star Wars Rebels has given us plenty battles between the Rebellion and the Empire. Predominantly focusing on a single cell operating out of Lothal, the show began to shift it's focus in Season Two with the introduction of other Rebels and adventures away from Ezra's (Taylor Gray) homeworld. This thread bears fruit as the Ghost transports Senator Mon Mothma (Genevieve O'Reilly, the actress who also played the role in Rogue One) to a secret rendezvous in order to bring the Rebels together and, for the first time, see the beginnings of a larger Rebel Alliance take shape.
Along with giving us Mon Mothma, "Secret Cargo" also highlights Ezra's skill as a pilot and Grand Admiral Thrawn's (Lars Mikkelsen) ability to anticipate and squeeze the Rebels far better than any other Imperial officer we've seen. Yes, the Ghost escapes to deliver the senator to her rendezvous, but only by evading Thrawn's grasp by the edge of their teeth. Sooner or later the Rebels will have to deal with the Grand Admiral if any of them hope to stick around long enough for a certain desert planet farm boy to come of age and reach for the stars.