But that is... not what we are doing.Abandoning the "your players can make a difference!" approach and adopting the Dragonlance method
There is no set ending that we are headed towards. At all. What happens in the adventures released will have an effect. We have never deviated from this.
In general, in the early part of the war, Travellers are placed in more minor areas and their actions can have more minor effects - but those can snowball later on. It is about planting seeds. Tilting the balance towards one side or the other on a backwater world may just seem to be a mark on a map, but when one fleet later has to dedicate fleet resources that it had planned to send elsewhere to take advantage of or shore up that world... that has an effect on the big picture.
That said, there have already been some fairly major points that Travellers can alter. Opening Moves springs to mind and, if this is the sort of thing you want to feature in your games, then by the Iridium Throne, keep an eye out for Favourites at Court...
As an aside, someone mentioned wanting to keep track of fleet positions and resources on the strategic side. This was never going to happen. That is not an RPG. Now, it could happen at some later point, either as a boardgame or video game maybe, but the whole point of this series is to strap your players into the front seats of the war where they will see what is happening and, yes, begin to alter things.