Have the inhabitants of Middle-earth ever used siege engines?

Question

When Fingolfin faced the Thangorodrim, apparently he didn't really know what to do, other than noticing that it would not fall from the voices of trumpets.

Did anyone (other than Morgoth, Sauron, Saruman, corrupted Númenoreans and perhaps the Lost Tales version of the Elves of Gondolin) in The Silmarillion and the Lord of The Rings construct and use siege engines or other mechanic artillery?

Do we have any reference from the books for crossbows?

Were the explosives used in the War of the Ring to breach Helm's Deep and the Rammas Echor a new, evil invention, or were used before it?

Answer 1

It is very unlikely that any of the good folk used advanced siege machinery.

In the books, there is little to no description of what a siege is in Tolkien's world. Even with Angband or Mordor's siege, there is little more than mentions of "bolts". The only time the words "catapult" or "ram" come into play is for Gondor's siege, and it was laid by Sauron.

In his numerous depictions of good versus evil, it is indeed the bad guys who tend to use technology for war and domination. Most of the good folk, even dwarves, use their skills for creation, not destruction.

There is actually a very good reason in-universe for this: the old builders made almost invincible fortresses.

Dwarves were safe from siege weapons inside the mountains. The enemy have to dig their own tunnels, break the door or find some hidden passages to hope for any invasion.

The old Númenóreans were mighty builders, as their legacies stand proof: first quote is from Pippin, when narrating the Ent siege of Orthanc, second is before Sauron's catapults fired their wicked explosive projectiles.

(Pippin) Many of the Ents were hurling themselves against the Orthanc-rock; but that defeated them. It is very smooth and hard. Some wizardry is in it, perhaps, older and stronger than Saruman’s. Anyway they could not get a grip on it, or make a crack in it; and they were bruising and wounding themselves against it.

_{LotR, The Two Towers, ch. 9: "Flotsam and Jetsam"}

At first men laughed and did not greatly fear such devices. For the main wall of the City was of great height and marvellous thickness, built ere the power and craft of Númenor waned in exile; and its outward face was like to the Tower of Orthanc, hard and dark and smooth, unconquerable by steel or fire, unbreakable except by some convulsion that would rend the very earth on which it stood.

_{LotR, The Return of the King, ch. 4: "The Siege of Gondor"}

As for the Elves, most of them relied on subtlety and magic. Lorien's forest wasn't protected with stone walls; and before Doriath, the kingdom of Thingol, had some kind of magical mazes made by Melian, to protect themselves from the dark rule of Morgoth.

So what was the plan of "good folk" when laying siege to evil fortresses?

The answer is hunger:

But some answered: ‘While we yet live? How long? He has a weapon that has brought low many strong places since the world began. Hunger. The roads are cut. Rohan will not come.’

_{LotR, The Return of the King, ch. 4: "The Siege of Gondor"}

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As for your remaining question, I would say that the explosives were not entirely unheard of for anyone that studied military lore against Sauron.

Not only does Aragorn shout "Devilry of Saruman", he also points out that "[the orcs] have lit the fire of Orthanc beneath our feet". Such explicit naming undoubtedly means he's well aware of Saruman's trickery and where they come from originally.

Additionally, it can be noted that there is some reference to "a fire" for Morgoth's army:

Many now fled to the Havens and took refuge behind Cirdan's walls, and the mariners passed up and down the coast and harried the enemy with swift landings. But in the next year, ere the winter was come, Morgoth sent great strength over Hithlum and Nevrast, and they came down the rivers Brithon and Nenning and ravaged all the Falas, and besieged the walls of Brithombar and Eglarest. Smiths and miners and makers of fire they brought with them, and they set up great engines; and valiantly though they were resisted they broke the walls at last.

_{*The Silmarillion *, ch. 20}

Answer 2

They are mostly not directly named, but Gondor was attacked with massive catapults and siege towers and of course the massive ram named "Grond." Gondor was in turn defended by smaller weapons that would probably be considered ballistae and catapults.

Quoting from The Return of the King, Book V, Chapter 4, "The Siege of Gondor":

Busy as ants hurrying orcs were digging, digging lines of deep trenches in a huge ring, just out of bowshot from the walls; and as the trenches were made each was filled with fire, though how it was kindled or fed, by art or devilry, none could see. All day the labour went forward, while the men of Minas Tirith looked on, unable to hinder it. And as each length of trench was completed, they could see great wains approaching; and soon yet more companies of the enemy were swiftly setting up, each behind the cover of a trench, great engines for the casting of missiles. There were none upon the City walls large enough to reach so far or to stay the work.

Which tells us two things; that the armies of Mordor had massive "engines" and that the forces of Gondor also had engines, but not large enough to hinder Sauron's forces at this time.

Mordor's engines are named "catapults" in the succeeding passage:

But the engines did not waste shot upon the indomitable wall. It was no brigand or orc-chieftain that ordered the assault upon the Lord of Mordor's greatest foe. A power and mind of malice guided it. As soon as the great catapults were set, with many yells and the creaking of rope and winch, they began to throw missiles marvellously high, so that they passed right above the battlement and fell thudding within the first circle of the City; and many of them by some secret art burst into flame as they came toppling down.

The effects of the defenders' engines are described a bit later as Grond is rolled up to the Gate:

But about the Gate resistance still was stout, and there the knights of Dol Amroth and the hardiest of the garrison stood at bay. Shot and dart fell thick; siege-towers crashed or blazed suddenly like torches. All before the walls on either side of the Gate the ground was choked with wreck and with bodies of the slain; yet still driven as by a madness more and more came up.

So the defenders' engines are capable of casting "shot" (rocks, implying a catapult) and "darts" (bolts, implying a ballista), with sufficient force to destroy a siege tower, which means they can't be personal or hand weapons.

The defenders' engines also take their toll on the great beasts of the armies of Mordor:

A mist was in Merry's eyes of tears and weariness when they drew near the ruined Gate of Minas Tirith. He gave little heed to the wreck and slaughter that lay about all. Fire and smoke and stench was in the air; for many engines had been burned or cast into the fire-pits, and many of the slain also, while here and there lay many carcasses of the great Southron monsters, half-burned, or broken by stone-cast, or shot through the eyes by the valiant archers of Morthond. The flying rain had ceased for a time, and the sun gleamed up above; but all the lower city was still wrapped in a smouldering reek.

_{The Return of the King, Book V, Chapter 8, "The Houses of Healing"}

Answer 3

In addition to the nice answer by @Tjafaas:

There is Grond, the battering ram used by Sauron's orcs during the battle of the Pelennor Fields, to breach the gates of Minas Tirith. It appears to mainly be the work of engineering rather than "sorcery", unlike the explosives of unknown nature that Saruman used at Helm's Deep.

If mobile archer towers count as "siege engines", then there's Oliphants for that. Though it would seem that their main use was to trample and create chaos among enemy ranks, similar to how Hannibal used them in the real world Punic Wars. (And this tactic can backfire, as we can see when Faramir's rangers attack an Oliphant to make it run amok among it's allies.)

As for catapults, trebuchets and the like, there is aren't many references of such in the books. In some of the great wars of the First Age, Morgoth had fire- and toxic breathing dragons which would probably achieve the same things as catapults.