As depicted in the trilogy:
In fact, he was never physically involved in (any) battle ever since his duel with Isildur. In spite of noticing Frodo and Sam near Mount Doom, he never really comes out (physically) to block them from destroying the Ring.
Was he limited by his physical condition or he was not willing to battle without the Ring? What was the reason?
He had indeed already taken a physical form, at least to some degree, for he was the Necromancer mentioned in the Hobbit, whose realm bordered upon Mirkwood. But at that point he had not regained a large portion of his power and worked mostly in secret.
He also greatly feared two things. First, the return of Númenor's heir, Aragorn, and the sword reforged. Unlike in the movies, in the books Aragorn left Rivendell with the sword reforged from Narsil and did not hide who he was, though he didn't travel openly as such.
The second thing he feared was that his agents had not found the One Ring. While there still remained the chance his enemies had it or might find it before he did, he could not risk exposing himself directly while he was in his much weakened state. Had he gotten the Ring, he would very likely have not hid in Barad-dûr while the Nazgûl lead his armies against Middle-earth.
Book 5, Chapter 4:
'Is Faramir come?' [Denethor] asked.
'No,' said Gandalf. 'But he still lived when I left him. Yet he is resolved to stay with the rearguard, lest the retreat over the Pelennor become a rout. He may, perhaps, hold his men together long enough, but I doubt it. He is pitted against a foe too great. For one has come that I feared.'
'Not – the Dark Lord?' cried Pippin, forgetting his place in his terror.
Denethor laughed bitterly. 'Nay, not yet, Master Peregrin! He will not come save to triumph over me when all is won. He uses others as his weapons. So do all great lords, if they are wise, Master Halfling. Or why should I sit here in my tower and think, and watch, and wait, spending even my sons? For I can still wield a brand.'
Sauron had a terrible track record in personal combat. He was defeated by Huan, Isildur and even fled before the White Council from Dol Guldur. I think he was much more a 'behind the scenes / manipulator' than a combat juggernaut.
At least in the movie, he had not yet attained a physical body. He needed his Ring, and the power he had poured into it, to complete his rebirth.
In the book, it was different - he had some physical form, but his powers were greatly reduced. He was still vulnerable, and could potentially have been killed. Why would he risk himself, when he knew (not thought, KNEW) that his armies were sufficient to the tasks at hand?
Alright, lots of wrong answers here :
a) Sauron cannot be killed without destroying the ring
b) Sauron wasn't "that" weak at the time, he was confident that his armies would succeed (which they would have if the ring had not been destroyed, with ease, the armies of both the Minas Tirith assault and the Barad-dûr siege being "not much" to him)
c) Sauron's power was more than decent when the siege of Barad-dûr occurred and it does not seem (after the books) that even Aragorn + Gandalf could have defeated him. (Again, power here is far beyond just raw power, it's about his control over the other rings, including the power of the Nazgûl themselves, the shadow, the eye, the fear, etc.)
d) Sauron disliked the presence of Aragorn as he saw in him the risk of a second Elendil / great alliance. This is much more related to his ability to bring light and protect Sauron's enemies from the paralyzing fear than to his relative combat potential. (All of Aragorn's major wins against Sauron are leadership wins, convincing the Rohirrim, convincing the ghost army, etc.)
e) Sauron did not care about that fight, the foolish alliance army was going to be crushed in front of his gates so why even bother.
Well that's just wrong . Sauron was probably the greatest of the Maiar, just as his master Melkor (Morgoth Bauglir) was the greatest of the Valar. For much weaker Maiar, just take a look at Radagast (LotR) or The Silmarillion/Unfinished Tales (much about weaker Valar in there too).
Among the Istari, it would seem that Saruman was once the most powerful, got replaced by Gandalf during his fall - and that there were other weaker Istari.
It is the way of Dark Lords, especially those in Middle-earth, to remain safely behind and secure in their place of power while using others as tools and weapons. Sauron's boss, Morgoth, was the same way. From The Silmarillion:
In Angband Morgoth forged for himself a great crown of iron, and he called himself King of the World... that crown he never took from his head, though its weight became a deadly weariness. Never but once only did he depart for a while secretly from his domain in the North; seldom indeed did he leave the deep places of his fortress, but governed his armies from his northern throne. And once only also did he himself wield weapon, while his realm lasted.
For now, more than in the days of Utumno ere his pride was humbled, his hatred devoured him, and in the domination of his servants and the inspiring of them with lust of evil he spent his spirit.
On that one occasion when Morgoth did wield a weapon, things didn't go exactly as he had hoped. He fought Fingolfin, High King of the Noldor, but only reluctantly. From The Silmarillion:
And Morgoth came. That was the last time in those wars that he passed the doors of his stronghold, and it is said that he took not the challenge willingly; for though his might was greatest of all things in this world, alone of the Valar he knew fear. But he could not now deny the challenge before the face of his captains; for the rocks rang with the shrill music of Fingolfin's horn, and his voice came keen and clear down into the depths of Angband; and Fingolfin named Morgoth craven, and lord of slaves.
[...]
Many times Morgoth essayed to smite him, and each time Fingolfin leaped away, as a lightning shoots from under a dark cloud; and he wounded Morgoth with seven wounds, and seven times Morgoth gave a cry of anguish, whereat the hosts of Angband fell upon their faces in dismay.
While Morgoth was victorious, he did not come out of the battle looking good; he was wounded by a mere elf, and never again came forth. Given that Morgoth was Sauron's teacher, we can imagine that Sauron got the message - don't fight your own battles!
Nonetheless, we do see Sauron engaging in combat himself a few times throughout the legendarium.
In the tale of Beren and Lúthien in The Silmarillion:
Therefore [Sauron] took upon himself the form of a werewolf, and made himself the mightiest that had yet walked the world; and he came forth to win the passage of the bridge.
[...]
Then Huan sprang. There befell the battle of Huan and Wolf-Sauron, and the howls and baying echoed in the hills, and the waters on the walls of Ered Wethrin across the valley heard it afar and were dismayed.
But no wizardry nor spell, neither fang nor venom, nor devil's art nor beast-strength, could overthrow Huan of Valinor; and he took his foe by the throat and pinned him down. Then Sauron shifted shape, from wolf to serpent, and from monster to his own accustomed form; but he could not elude the grip of Huan without forsaking his body utterly.
Sauron was humiliated in battle against a dog.
We know little of Sauron's actions during the War of Wrath that brought down Morgoth; but we do know that he fled from battle, and refused to return to the good, for fear of humiliation.
We know little as well of Sauron's actions during the second age, beyond teaching the elves the craft of Ring-making. We do know that he felt unable to defeat the Númenóreans in open battle, so he surrendered to them and corrupted Númenor from within.
We do know that Sauron fought personally against Gil-Galad and Elendil in the war of the Last Alliance, and that he was defeated and overthrown by them. That was when he lost the Ring.
So throughout the Legendarium, we see again and again, when Dark Lords fight directly, they lose, or they are humiliated.
Sauron had no desire to fight anyone. He took delight in commanding others to do things, not doing them himself. He would only enter battle personally as a last resort, when no other avenue is open to him. The battle at the Black Gate was not such a last resort. That was simply the destruction of an arrogant fool coming with too little force.
Sauron came to personally fight in battles on several occasions:
the First Age: assault on Minas Tirith on isle of Tol Sirion staffed by entire garrison of elven warriors of Noldor kindred with elf-lord Orodreth in the lead. Successful for Sauron, fortress turned into watch-tower for Morgoth.
the First Age: duel of magical nature ("songs of power") with great elf-lord Finrod Felagund. Successful.
the First Age: fight with combined power of mystical creature Huan (fate and prophecy involved) and Lúthien powerful half-Maia, half-elf being. At first Huan almost withdrew until Lúthien incapacitated Sauron with her magic and Huan took advantage; in the end fate subverted Sauron's doings because he wasn't the one destined to kill Huan. Ends with strategic withdrawal after Lúthien let him go.
the Second Age: duel with Celebrimbor during War of Elves and Sauron, personally leading his armies to Eriador. ("Celebrimbor, desperate, himself withstood Sauron on the steps of the great door of the Mírdain; but he was grappled and taken captive, and the House was ransacked...") Successful for Sauron, destruction of Eregion, though in the end entire war campaign ended with defeat because his armies were decimated and remained he alone with only his bodyguard.
The Second Age: War of the Last Alliance (in war against Númenóreans; Sauron did not take part personally, he "made no offer for battle" as part of his voluntary cunning plan), the last stages, even though a bit weakened (he needed time for bodily rehabilitation and gaining control over his former subjects), but with the One Ring still, so more powerful with it than without. At first successful, with a sortie he personally broke the 7-year long siege of Barad-dûr and drove armies of Elves and Númenóreans miles away from fortress to the slopes of Orodruin where the final combat with Elendil, Gil-Galad and Isildur happened, (Círdan Shipwright and Elrond Half-elven also present) which ended with death of both Elendil and Gil-Galad and Isildur possibly dealing 'death-blow' to temporarily incapacitated Sauron and taking his Ring from his body.
So, no I don't think it's a 'terrible track record in personal combat' rather quite good one, all things considered.
But in the end Sauron is a commander, strategist, highest leader and as one he rarely gets things done by himself unless he has no choice. Being lord implies I think having subordinates other than yourself to fulfil your will, and this is main sphere of interest for Sauron to command others, the 'kingship' itself. He might have great power, mightier than any mortal but he still needed subjects and armies, because in the end with all his might he is still ONE being.
(1) The hosts of Men and Elves had no hope of winning.
Unfortunately, the movie fails to capture this important point: the enemy they had defeated in the plains of Pelennor was but a small fraction of Sauron's full might.
‘My lords,’ said Gandalf, ‘listen to the words of the Steward of Gondor before he died: You may triumph on the fields of the Pelennor for a day, but against the Power that has now arisen there is no victory...Hardly has our strength sufficed to beat off the first great assault. The next will be greater. This war then is without final hope, as Denethor perceived. Victory cannot be achieved by arms, whether you sit here to endure siege after siege, or march out to be overwhelmed beyond the River.
(2) Sauron didn't know about the Ringbearer at Mount Doom until it was too late
Gandalf:
That we should wish to cast him down and have no one in his place is not a thought that occurs to his mind. That we should try to destroy the Ring itself has not yet entered into his darkest dream.
Sauron becomes aware of this plan only moments before it is completed.
And far away, as Frodo put on the Ring and claimed it for his own, even in Sammath Naur the very heart of his realm, the Power in Barad-dûr was shaken, and the Tower trembled from its foundations to its proud and bitter crown. The Dark Lord was suddenly aware of him, and his Eye piercing all shadows looked across the plain to the door that he had made; and the magnitude of his own folly was revealed to him in a blinding flash, and all the devices of his enemies were at last laid bare. Then his wrath blazed in consuming flame, but his fear rose like a vast black smoke to choke him. For he knew his deadly peril and the thread upon which his doom now hung.
From all his policies and webs of fear and treachery, from all his stratagems and wars his mind shook free; and throughout his realm a tremor ran, his slaves quailed, and his armies halted, and his captains suddenly steerless, bereft of will, wavered and despaired. For they were forgotten. The whole mind and purpose of the Power that wielded them was now bent with overwhelming force upon the Mountain. At his summons, wheeling with a rending cry, in a last desperate race there flew, faster than the winds, the Nazgûl the Ringwraiths, and with a storm of wings they hurtled southwards to Mount Doom.
(3) It's not his style
Denethor:
He will not come save only to triumph over me when all is won. He uses others as his weapons. So do all great lords, if they are wise, Master Halfling.
In the Silmarillion, Sauron is Morgoth's chief lieutenant, yet he principally relies on deception and illusion, rather than participating personally in battles (unlike, say, Gothmog).
Recall that Sauron was once personally defeated, even while he wielded the One Ring. After that downfall, and now without his Ring of Power, there's even less motivation to take such a personal risk, particularly for a battle whose outcome is certain regardless.
We don't know how much strength Sauron had regained by this time. Probably quite a lot. In any case, there wasn't a reason for him to participate personally in these events.
The answers are pretty clear from the books and the movies, and mostly touched upon by others, but not quite strung together.
1) Compared to his gathered strength, the "distraction army" was very weak, and stood no chance of surviving that battle with his forces in Mordor. Indeed, the suicide mission was meant to be a distraction, and Aragorn and Gandalf included themselves because the army, itself, probably was not significant enough to command his whole focus.
2) Comparatively speaking, Sauron was weak. Even at the peak of his strength, with the Ring, Isildur was able to cut it from him and so weaken him that it took a few thousand years to recover. If he wasn't weak, he really wouldn't care about recovering his Ring. So, physically, especially with the heir of the Sword of Elendil, that did that cutting, and the actual sword, when combined with my point #1 - there was no reason to risk someone hitting the battlefield lottery just for vanity of being there in person. Heck, a Hobbit and a woman just took out his #1 general. Why take chances?
3) See #2 - Sauron was weak. Think about what happened a couple of times in the movies and the books - Frodo puts on the Ring, at Mt Doom. Sauron's attention turns inward, his entire army hesitates/falters, and his Eight Ringwraiths get recalled. Then, after he falls, the entire assembled host breaks into completely unfocused bedlam and chaos and are easily wiped out by both the cataclysm and the assembled armies of the West. A few minutes before, they were overwhelmingly stronger, not just sword and spear fodder.
In his weakened state, Sauron needed to focus on his armies. His will/spite/malice is what kept all the orcs (think of how they slaughtered each other at the drop of a hat when they had Frodo), mindless trolls and other creatures focused and on task. With the Ring, that was probably a much more effortless endeavor. Without it, it needed his unwavering focus to keep a mob naturally inclined to chaos working with a purpose. Compared to being in the tower, overlooking things, isolated from all else, physically participating in the battle would have been a pretty big distraction.
As for the question of why he didn't come out to confront Sam and Frodo at the Crack of Doom, he was 50 miles away when he noticed them. He wouldn't have had time to get there.
Part of the story's attraction for readers is that Sauron himself never appears. We get reports of him from other characters, but Sauron never appears in person.
Pippin tells afterwards of what he saw in the palantír of Orthanc. Denethor and Aragorn report on what they saw of Sauron when they themselves looked into a palantír. Gandalf describes, afterward, his secret visit to Sauron's fortress of Dol Guldur. Smeagol describes his memories of being held prisoner in the Dark Tower.
Of all the characters, Frodo comes closest to actually meeting him in front of us, so to speak, when he looks into the Mirror of Galadriel, or when he is wearing the Ring on Amon Hen.
The character of Sauron is bolstered by the air of mystery which surrounds him as a consequence of his never being seen. Everything the reader learns about him is filtered through the impressions of some other character: we are always kept at a distance. That air of mystery greatly strengthens the tale, from a literary perspective.
In the same way, the trilogy is rich in descriptions of the Elder Days: various characters give an account of some distant historical event, usually heroic in nature, from battles with the dark power thousands of years earlier. Those accounts gain much of their potency from the vast distance from which we glimpse the events. Too much detail would spoil the air of mystery which surrounds those tales of the Elder Days; and so it is with Sauron. He needs to be a shadowy figure, because much of his power to dominate the story comes from the ever present air of mystery surrounding him.
Addendum - The trilogy is, after all, entitled The Lord of the Rings. Sauron is thereby the eponymous character, brought to mind on every page by the title printed at the top of the page. In literary terms, he thereby is the most significant character in the book. And Tolkien takes a deliberate decision to keep him in the shadows: it is not by accident that he does not appear. He is the Dark Lord, he cloaks himself in darkness in the tale; and so the author must cloak him in darkness too, metaphorically speaking, else everything which the author is doing to build up tension in the storyline will dissipate: we learn only what Frodo learns, and Frodo must have a fear of what lurks in the darkness if he is to successfully convey that to the reader.
