Legolas has killed at least twenty Uruk-hai with his bow

The postern was closed again, the iron door was barred and piled inside with stones. When all were safe within, Éomer turned: ‘I thank you, Gimli son of Glóin!’ he said. ‘I did not know that you were with us in the sortie. But oft the unbidden guest proves the best company. How came you there?’

‘I followed you to shake off sleep,’ said Gimli; ‘but I looked on the hillmen and they seemed over large for me, so I sat beside a stone to see your sword-play.’

‘I shall not find it easy to repay you,’ said Éomer.

‘There may be many a chance ere the night is over,’ laughed the Dwarf. ‘But I am content. Till now I have hewn naught but wood since I left Moria.’

‘Two!’ said Gimli, patting his axe. He had returned to his place on the wall.

‘Two?’ said Legolas. ‘I have done better, though now I must grope for spent arrows; all mine are gone. Yet I make my tale twenty at the least. But that is only a few leaves in a forest.’

The Two Towers, Book Three, Chapter 7: Helm's Deep.