Fleet Admiral Firmus Piett was in command of the battle fleet assembled at Endor, and flew his flag aboard HIMS
Executor (ref.
Return of the Jedi[); it is known that there was at least one other flag officer aboard the
Executor, that being Piett's chief of staff, Admiral Chiraneau (ref. Death Star II Expansion Set), and one other flag officer present in the fleet as one of Piett's subordinate task force commanders, Admiral Harrsk (ref.
The Essential Chronology). Based on the fact that, despite being a post captain, Captain Gilad Pellaeon was only Executive Officer, HIMS
Chimaera (ref.
Star Wars Encyclopedia), it is very probable that the CO was either a line captain or a commodore (at the very least) and another one of Piett's task force commanders. Additionally, there were two 'fleet captains' present with Piett on the
Executor's bridge (ref.
Return of the Jedi novelization).
There were at least four grand admirals present – Grand Admirals Osvald Teshik, Nial Declann, Miltin Takel, and Afsheen Makati (ref. "Who's Who: Imperial Grand Admirals") – as well as a potential fifth grand admiral, possibly Rufaan Tigellinus's successor (ref.
The Essential Chronology), but – this is an important distinction – they were not present and
afloat (as it were); the grand admirals had arrived with the Galactic Emperor and were aboard the Death Star as observers, not in the battle fleet.
It is pretty safe to assume that Chiraneau died at either the same time or shortly after Piett was killed and the
Executor was destroyed. At that point, command of the battle fleet should have devolved upon the next senior officer present and afloat, which was probably Pellaeon's unnamed CO, as the Death Star II Expansion Set established that
Chimaera was the auxiliary communications ship (not the same as the main communications ship in the novelization, which was destroyed before the
Executor was), and
The Essential Chronology states that it was only after regrouping at Annaj that Harrsk was "unwilling to take orders from Pellaeon, a mere captain," which probably indicates that he did not realize it was Pellaeon and not his CO who had issued the order to retreat.
At least three Star Destroyers were destroyed prior to the destruction of the
Executor herself – (1.) a Star Destroyer destroyed by collision with a rebel cruiser (ref.
Return of the Jedi novelization), (2.) the main communications ship (op. cit.), and (3.) the Star Destroyer seen destroyed by turbolaserfire to the
Executor's starboard, possibly HIMS
Devastator (ref.
Return of the Jedi). Although the loss of the main communications ship very likely contributed to a degradation of Imperial coordination, the fact is that it could not have been excessively deleterious; both the
Executor and the
Chimaera remained intact. Even if one of Piett's task force commanders had been aboard, there remained Piett himself, Pellaeon's unnamed CO, and Harrsk (although his flagship did sustain damage, it was not destroyed, and the damage to his face was apparently superficial, despite the loss of an eye).
Lieut. Voren Na'al's Report to the Provisional Council of the Alliance of Free Planets on the Aftermath of the Battle of Endor – which is the notional document corresponding to most of chapter 2 of
The Truce at Bakura Sourcebook – notes that the destruction of the
Executor, which Na'al incorrectly attributes to "the Death Star's gravitational field" (seemingly unaware that she had been "having difficulties with its guidance system" even before Admiral Ackbar ordered the fleet to concentrate its fire on her, and had been "listing badly to starboard" when her bridge was hit, according to the novelization), "seemed to trigger a significant demoralization throughout the Imperial fleet – the accuracy of Imperial fire dropped off, and while the decrease was not substantial, it was at least noticeable," and that "several TIEs from the
Executor – on station with orders to protect the exposed sections of the Death Star – began to make crucial errors once their command ship (and source of coordination) had been destroyed," indicating that the
Executor herself had probably assumed much of the main communications ship's functions after she had been destroyed.
Although Grand Admiral Thrawn's 'borg-implant' theory (quoted in
Heir to the Empire) proved to be wrong in the details, it was essentially correct; Grand Admiral Nial Declann
had been applying his dark side mentalic influence to enhance the Imperial fleet via battle meditation (ref. "Who's Who: Imperial Grand Admirals"). The immediate result of the Galactic Emperor's death, therefore, was in fact magnified. As the novelization points out, the Galactic Emperor's death removed the "central, powerful evil that had been the cohesive force to the Empire" and left the dark side diffused and 'nondirected,' leading to confusion, desperation, and damp fear, and to this must be added the negative side effects of the abrupt termination of Declann's battle meditation (he stopped immediately when he felt the Galactic Emperor's death through the Force).
It is pretty safe to assume that Chiraneau was also killed when Piett and his two 'fleet captains' died aboard the
Executor, which would have sent command to the next senior officer, one of Piett's task force commanders, probably the unknown CO of the
Chimaera, which was the auxiliary communications ship. In any case, Na'al's report contains the following information:
The immediate effect of Death Star II's explosion was severe: ship-to-ship communications were almost completely disrupted. The Death Star possessed the main communications node for Imperial ships stationed in the Endor system. After the explosion, contact with the outside was lost along with the in-system HoloNet. In addition, the explosion itself caused considerable interference with both scanner systems and communications equipment. Imperial ships, accustomed to superior communications, were caught unprepared for the sudden reduction in communications range. Alliance troops, trained to operate under less than ideal conditions, pressed their assualts on various ships and the Imperials' unified blockade action degenerated into a series of fierce single engagements.
After hours of fighting, Imperial morale was extremely low, and it is this loss of (for lack of a better term) fighting spirit that led to the Imperial retreat. The Rebel Alliance, after years of fighting a defensive campaign, had defeated a numerically superior force and landed a decisive blow against the New Order.
Na'al's report is also quite explicit that "contrary to popular opinion, the Imperial fleet did not surrender after the Death Star exploded," and "in fact, the Alliance accepted no Imperial surrender at Endor," because "despite the battle's sudden reversal in momentum, the fighting raged on for nearly four hours." Nor was the battle a bloodless victory; Na'al quotes "casualty estimates for Alliance starfighter pilots" that "exceeded 20 percent," noting that "shipboard casualties nearly matched that total," and that "of the surviving Alliance vessels, nearly 75 percent of them needed extensive repairs before returning to duty" (unlike most sourcebooks,
The Truce at Bakura Sourcebook actually cites its sources; the 20% figure is drawn from
The Truce at Bakura, in which Ackbar states that the Alliance "lost twenty percent of our forces, battling only part of the Emperor's fleet").
Na'al writes in his report that the battle continued for "nearly four hours" after the destruction of the Death Star, and the Historical Council of the Galactic Federation of Free Alliances – of which Na'al was Archivist Emeritus – subsequently writes in
The New Essential Chronology that "after the destruction of the second Death Star, the Imperial fleet had continued to fight for four hours under the command of Grand Admiral Teshik – but were systematically beaten back by their numerically inferior foe," and that "when Rebel forces disabled Teshik's ship, Captain Gilad Pellaeon of the Star Destroyer
Chimaera ordered the fleet to retreat and regroup at Annaj, where the first signs of stress began to show" (note that the scribe writes in
The New Essential Guide to Characters that "with the death of Admiral Piett and the absence of any Grand Admirals, Pellaeon's order made him the de facto fleet leader at Annaj"). However, here one discovers a discontinuity, as "Who's Who: Imperial Grand Admirals" – the only one of these sources that is not notionally written from an 'in-universe' perspective, and thus not overtly known to be written by partisan historians – states quite plainly that "when the Imperial retreat was called, Teshik stayed behind," and "as a testament to Teshik's brilliance, the battle raged for another three hours before his Star Destroyer
Eleemosynary succumbed to overwhelming ion cannon fire."
Note here that the only source not written from an 'in-universe' perspective – "Who's Who: Imperial Grand Admirals" – states that Teshik fought for three hours
after the retreat was called, whereas the Historical Council's version – written at a time when Pellaeon had become not only "the dictator we can do business with" (it being in the New Republic's best interests that the legitimacy of his regime in the Outer Rim be upheld and that all other Imperialist states and neo-Imperialist movements be deprecated as 'non-mainstream,' leaving Pellaeon and his pro-New Republic regime as the 'legitimate' heirs to the Palpatinist tradition), but indeed a wartime ally of the New Republic during the Vong War and a leader of the Galactic Alliance's war effort in the Swarm War – claims that Pellaeon called the retreat four hours after the destruction of the Death Star,
after Teshik's
Eleemosynary was disabled. The scribe even goes so far as to claim that since there were no grand admirals at Annaj, Pellaeon was de facto in charge, ignoring several important facts: (1.) Grand Admiral Teshik was not present because he had been abandoned at Endor; (2.) Admiral Harrsk
was present at Annaj and would have automatically taken precedence before any ship's Commanding Officer, let alone an Executive Officer acting as captain after the death of his CO, who would take command only if every single other CO had been killed and he were the senior XO present; and (3.) not even Harrsk should have taken command, because Annaj was in fact
an Imperial Sector capital (a deposition given by Alliance Intelligence's Maj. Breslin Drake is quoted in
The Truce at Bakura Sourcebook as saying that "the nearest Imperial sector capital (and the next logical link in the chain of command) was Cannij Barr, Annaj system – a system nearly two days' Class One hyperdrive travel distant").
Immediately after the battle itself, Na'al did write that the space battle lasted nearly four hours after the destruction of the Death Star, and there is no reason to suspect his honesty. Combined with the knowledge that Teshik fought for three hours after the retreat, and the Historical Council's claim that his ship was captured toward the end of the fourth hour, it seems likely that the breakdown in communications had meant that most of the ships in the fleet were unaware that Teshik had made his way to the
Eleemosynary, and were looking to the
Chimaera's CO as the SOPA for orders. When the unknown CO was killed, Pellaeon assumed command and issued the order to retreat, possibly without announcing the CO's death (thus explaining Harrsk's subsequent outrage at Annaj, two days later), leaving Teshik behind to fight for another three hours before being captured.
As to why Pellaeon was not tried by court-martial, it is quite possible that he was spared by political expediency; there were, after all, two much more important figures among the Loyalists that had displayed outright cowardice at Endor – Grand Admirals Miltin Takel and Afsheen Makati, who had been aboard the Death Star and simply fled the battle altogether, not taking command as Teshik had tried to do, nor even regrouping with the fleet at the nearest Sector capital at Annaj. The fact that both Takel and Makati went unpunished and remained Loyalists as late as the start of the Trioculus Affair probably means that the decision was made to overlook any and all indiscretions by senior officers at Endor and in its immediate aftermath, so long as the officer in question had had the good taste not to defect altogether (as Harrsk and others had done).
As it happens, it is no great argument in Pellaeon's favor to claim that he was Thrawn's protégé; it need hardly be said that a man with over 50 years of naval experience shouldn't be learning much of anything about space warfare from anyone. Very likely he was chosen as Thrawn's flag captain – which is not the same thing as a second in command or a deputy supreme commander – because, while suffering from excessive conservatism, unaggressiveness, and lack of nerve, he is a competent and reliable administrator who was more than able to make his ship run like clockwork (which is, incidentally, precisely what an XO is expected to do); in
Tatooine Ghost it was mentioned that the
Chimaera was reputed as one of the best-run Star Destroyers in the Imperial fleet. Nevertheless, skill in organization does not imply skill on the battlefield (see, for example, Maj. Gen. George B. McClellan).