Set in 2799 TA. The battle mentioned is the Battle of Azanulbizar.
Twenty-nine years after Smaug's attack on Erebor and the breaking of ties between Erebor and Greenwood, an army of dwarves draws the elf king's attentions.
One followed another in a long line of people that seemed to stretch on forever. Legolas guessed that there were several hundreds of them. The scouts came first, then the standard bearers; those were followed by the royal family: King Thrór, decked in armor with precious stones so numerous that their white glitter caught the elven eye even from so far away; Crown Prince Thráin was no less brightly adorned, although his colors were darker, and with him were his sons Thorin and Frerin. And then came a vast army of warrior dwarves, supply wagons, healers, ponies and boars.
"Three hundred from Erebor," his captain Osean said to his right, "armed for war. They have their ... war pigs with them; heavy armor; wagons with provisions... and more come from the Iron Hills. Our lookouts have seen them."
"And what are they doing on the road south?"
"The army from the Iron Hills is not directed here but also southward. They're going around the forest, since they may not pass through it. Our informants in Dale say that the dwarves march on Moria."
"Moria?!" Legolas' eyes narrowed.
"Yes. A den of orcs and worse things. Yet Thrór seeks to reclaim that ancient dwarven hole."
"Foolish," the king pressed out through his tight jaw. Was there no end to dwarven idiocy?
Almost thirty years had passed since they had drawn a dragon to their kingdom, causing the death of hundreds of men and elves. It appeared that nothing had changed. Again they sought strife and war, most likely walking to their own death.
"Keep a close watch on them," Legolas instructed.
"Yes, Sire."
No longer did Legolas expect to see his father behind his shoulder when he heard the title. But today, he thought he could feel his father's gaze on him, and he wondered whether Thranduil would be proud, or at least approve of him. He supposed that of the latter he could be pretty certain: his father had never liked dwarves.
It took almost two months until Legolas heard of the dwarves again.
"They return diminished," he was told, and he went again to the edges of the forest and climbed a high beech with blood-red leaves to watch.
A mere fraction of dwarves returned to the Lonely Mountain that day, led by Thorin alone.
"Thrór and Thráin are dead then?" He asked.
"Thrór yes, beheaded by Azog named the Defiler. Thráin's fate is less certain, we have heard. Lost in battle he was, but not among the dead. He may have been taken prisoner, but none have come forth to brag about it, and Moria, though many orcs died defending it, was not conquered."
"They failed then."
"Yes, and many paid for it. Prince Frerin was among the dead, and many other old, valued commanders."
"At least this time, those to blame were also the only ones to bear the cost," Legolas only said, and there was dark satisfaction in his voice.
Osean nodded next to him.
"Only Prince Thorin remains of the line of kings, and he gained a sobriquet: they call him Oakenshield now."
"Do they?" Once he would have been curious; now his eyebrows drew together into a fierce frown reminiscent of Thranduil and he said: "It changes nothing. There can never be friendship between elves and dwarves, no matter who sits upon the throne of Durin."