Spoilers ahead....There seem to have been alot of changes in position over the course of the war. First it started out like this, during "A Time to Stand":
Sisko is just captain of the Defiant
Martok is just captain of the Rottaren
Ross is some type of important commander. Could he be the suprememe commander of the ill-fated 7th fleet?
Over the course of the season 6 war arc, we saw sisko move to some more important position as one of ross' advisors.
By "You are Cordially Invited," the station has been retaken. At this point....
Sisko is just captain of the defiant and DS9
Martok is supreme commander of the 9th fleet
Ross disappears....Maybe he has gone back to starbase 375 to continue to command the 7th fleet, or some other force.
It seems it stays pretty much that way until "Tears of the prophets":
Sisko is named commander of the invasion of cardassia.
Martok is still commander of the 9th fleet.
Ross reappears before the battle, but then disappears.....It seems possible that more than one fleet was used in the invasion of chin'toka. Maybe Ross' 7th fleet (back to at least half strenght as metnioned in some other obscure episode) also participates in the invasion, but perhaps ross himself stays behind.
After this point Ross appears on the station several more times, such as in "Take me out to the Holosuite." Maybe by this point the 7th fleet also operates out of DS9, along with the 9th.
Ross' importance changes by "The Emeperor's New Cloak." In this episode, Martok mentions he'll ask Gorwron for more ships, and Sisko says he'll ask admiral ross for more ships. I believe it is possible that by this time Ross has been placed in charge of all federation forces fighting in the dominion war.
Overtime, i believe things start to change. Because by the 7th season arc, Martok is mentiones by Gorwron to have been commanding the entire klingon war effort. Perhaps by this point martok was put in command of all klingon forces operating in the dominion war.
So, by the time of the finale, things stand as follows:
Sisko is still in command of the invasion of cardassia. This includes commanding the battle of carddassia prime.
Martok, now channcelor, is in command of all klingon forces.
Ross is in command of all federation forces fighting in the dominion war.
Thoughts?
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"How many people does it take before it becomes wrong?"- Jean-Luc Picard
"Fortune Favors the Bold."- Benjamin Sisko
"And so, the warriors, the peacemakers, the helpers, the saviors, the forgotten, and the remembered, they all signed on that data padd and peace was made."- Shannon London-Karkarsku, leader of the Unisist Movement
Captain Alex Herenwhiner,
Transwarp inter-dimension timeship explorer U.S.S. Liberty