Any dialogue you recognise is taken from LOTR: ‘The Black Gate Opens’, and ‘The Field of Cormallen’. Because I can’t write better than Tolkien.

The Black Gate was before them, high and impenetrable, and the host was arrayed on the desolate ground in front of it. During the last hours of the dreadful ride towards Mordor, Denethor had taken counsel with Aragorn and Gandalf. It had been decided to place the banners of the Rohirrim and of Dol Amroth and the other allies of Gondor with the army, but that Meneldil and the standard bearer of Denethor should be behind Denethor and Aragorn at the forefront of the host. As he had proposed the plan, Denethor had been very formal and impersonal – it was clear that in his heart he did not want it, but that he had no choice.

Now they waited, the black and the silver side by side, and raising a gauntleted hand Denethor called the heralds forward. There was a blast of trumpets.

“Come forth!” the heralds cried. “Let the Lord of the Black Land come forth! Justice shall be done upon him. For wrongfully he has made war upon Gondor and wrested his lands. Therefore the Lords of Gondor demand that he should atone for his evils, and depart then forever. Come forth!”

They waited. Behind the captains the men stood still as statues, and silence fell over the host. High above the Nazgûl circled, and the air was dusty. For a long time nothing happened. Denethor seemed to be about to call the retreat, when at last there was a roll of drums that shuddered, making the ground shake, and the Gate opened.

From it rode a small company all in black, with a standard blowing high above emblazoned with the Lidless Eye. At the head of the embassy was a man in sable, mounted upon a horse that seemed more demon than beast. Denethor gripped the reins of his horse, but held fast.

The messenger rode up to the waiting captains and looked at them, his dark eyes glinting from behind his helm. He looked first at those in the second row: Legolas and Gimli, Pippin, quavering but holding his nerve, Elladan and Elrohir, Imrahil of Dol Amroth and Éomer of Rohan. Then his gaze switched to the three in the forefront: Aragorn, Denethor, and Gandalf. Finally he spoke, his voice mocking and cold.

“Is there anyone in this rout with authority to treat with me? Or indeed with wit to understand me?”

“You speak to the Steward of these lands taken unlawfully,” said Denethor. “That is authority enough.”

“Indeed?” laughed the messenger. “Lofty words from a Steward who holds on to the reins of his power with only his fingertips, and who suffers the banner of the traitor kings to be lifted above him.” He looked at Aragorn, and laughed again. “And thou, who wouldst be king, and yet will not seize the kingship, and dares to trespass on the Lord Sauron with such a pathetic rabble as this – what say you?”

Aragorn said nothing, instead holding the messenger’s gaze without moving. Nobody stirred, until the messenger shrank in his seat and his horse stepped back. “I am a herald and an ambassador, and may not be assailed!” he cried.

Gandalf touched Shadowfax with his heel, and the horse moved forward, the light glimmering around rider and mount. “Where such laws hold,” the wizard said, “it is also the custom for ambassadors to use less insolence.”

“So! So thou art the spokesman, old greybeard? That is good, for I have tokens that I was bidden to show to thee in especial, if thou shouldst dare to come.”

One of the guards rode forward and presented a bundle wrapped in black cloths to the messenger. From the cloths, he drew three items that made Pippin exclaim in horror. Glancing sharply at Aragorn, Denethor raised an eyebrow in question, but Aragorn shook his head slightly. Gandalf silenced Pippin with a word.

“So you do not deny these tokens?” the messenger said, glee in his tone.

“I do not wish to deny them,” replied Gandalf. “Indeed I know them and all their history. And you cannot say as much.”

“Dwarf-coat,” said the messenger, holding up a glittering mithril shirt, “elf-cloak,” displaying a grey cloak like to Aragorn’s, “blade of the downfallen West,” showing a short sword, “and spy from the little rat-land of the Shire. The marks of a conspiracy. We will return these to you, when you agree to certain terms that the Lord Sauron has deigned to offer you.”

Gandalf still held the messenger’s eyes, steadily, but age seemed to have descended upon him. “Name the terms,” he said.

In silence they listened as the messenger recited Sauron’s demands, and Denethor’s shoulders sagged. “All hope is gone,” he breathed. “Your quest has failed; it has robbed me not only of my son but also of my lands. What is there left?” His horse shifted, and Denethor made no move to restrain it. Aragorn reached out and caught the reins.

“My lord Steward!” he hissed, watching the messenger out of the corner of his eye. “Hold firm!”

Denethor looked at Aragorn through shadowed eyes. “Hope is gone,” he repeated.

“These are the terms,” said the messenger. “Take them or leave them!”

Gandalf moved, throwing back his cloak. A white light broke free as he rode forward and grasped the tokens. “These we will take, in memory of our friend,” he said. “As for your terms, we reject them utterly. Get you gone, for your embassy is over and death is near to you. We did not come here to waste words in treating with Sauron, faithless and accursed; still less with one of his slaves. Begone!”

The messenger recoiled under his anger, and turned his horse. The embassy from Mordor galloped back inside the Gates, and then a trumpet rang out, loud and harsh.

“Battle is upon us!” cried Aragorn. “My lord Denethor ... will you order your forces?”

Denethor was breathing hard, his face pale as death, and he looked at Aragorn as if he did not see him. Hesitating only a second, Aragorn pulled at the reins of the Steward’s horse and turned it around.

“Elrohir!” he called, and his foster-brother turned and was with him in a moment. “Lead the Steward to that ground over there,” Aragorn said. “And stay with him.” Elrohir nodded. “Éomer! Go to your men, battle formation, ready to charge when something comes out of that gate.”

Éomer nodded, raising his sword in salute, and galloped off towards the Rohirrim. Imrahil was already moving towards his own forces, and Aragorn nodded in thanks as the Prince hurried away.

“Pippin, get back to your company.” The hobbit turned a frightened face up to him, and Aragorn wished he could comfort him. But there was no time. “Go! Elladan, to the Rangers. Legolas, there’s raised ground over there; join the archers and try and pick off as many as you can.”

Now there was only himself and Gandalf left before the Gate, with Meneldil and the sable standard of Arwen close by. Gandalf smiled. “The last battle, my friend.”

“May it be swift,” Aragorn returned, and kicked Roheryn into a canter, crossing to a mound of earth opposite from the one he had sent Legolas to. Meneldil followed and planted the banner firmly.

Aragorn drew his sword, and raised the blade high in the air. “Men of Gondor!” he cried. “Now is the hour of doom! Fight for your freedom, and be not afraid!”

The men around him cheered, even as the Gate opened again and the first assault began to pour out. His heart beating faster as the adrenalin set in, Aragorn swept his sword down in a shining arc and called, “Now!”

From his right, a rain of arrows was set loose as Legolas and a band of archers from Ithilien and Minas Tirith launched their assault. At the same time, the Dúnedain with Elladan in their midst swept forwards, with Imrahil and the knights of Dol Amroth attacking from the other side. Arrows were coming from the ramparts alongside the Gate now, and Orcs and other evil creatures poured from the Gate itself.

Aragorn raised his sword again, and with a cry galloped into the battle.

Around him there was the familiar sound of men’s cries as they fell; the roar of Orcs and the screaming of fell beasts mixing with the clash of blade on blade. Andúril was glowing with the fire of combat, and Aragorn let himself fall into the rhythm – blade sweeping round and down, a stab, a cut, a slash ... Roheryn stumbled and he swung himself off the horse’s back, giving it a hard push to send it away out of danger. On foot now, he moved through the enemy forces cutting a swath before him.

Out of the corner of his eye Aragorn saw a long blade, and he intercepted and turned to face the new opponent. Instead, he saw Denethor’s face, a cut marring the Steward’s cheek. Denethor had lost his helm and was fighting bareheaded, but he looked strong and his eyes were shining. Both men lowered their swords for a moment, and Aragorn smiled before turning and attacking an Orc. Behind him, he felt the Steward do the same, and the two men began to fight back to back, each protecting the other as one Orc after another came at them.

They had been fighting like that for only a short amount of time – though it seemed hours – when Denethor cried out. Swivelling even as he decapitated an Orc, Aragorn took in the troll looming above the Steward. He lunged and stabbed upwards, Andúril parting the beast’s flesh easily; and as the troll fell Aragorn pulled Denethor out of the way and to his feet.

“I thank you,” Denethor panted, and seemed to be about to say something more, when the world stood still. The hosts of Mordor paused, and the hosts of Gondor stayed their blows, and the Nazgûl in the air above shrieked and whirled away towards the East. Louder than all the noise of battle came Gandalf’s voice, crying, “The Eagles are coming!”

Aragorn’s eyes glittered, as full-fledged hope returned to his heart, and with the men around him he echoed the wizard’s voice. “The Eagles are coming!”

And the men of Gondor and of Rohan, of Dol Amroth and of the North, renewed their efforts and struck with fresh vigour at their enemies. Then the earth trembled under their feet, and Gandalf cried again, his arms high in the air and a great light around him, “Stand, Men of the West! Stand and wait! This is the hour of doom.”

The earth shook again, harder, and with a crash the Gate tumbled to the ground, the ramparts crumbling. In the air a flame lit the sky, and noise filled the air.

Then, there was silence.

“The realm of Sauron is ended!” said Gandalf. “The Ring-bearer has fulfilled his Quest.”

Aragorn leant on his sword, and the tears of joy began to roll down his cheek.