[narfforc]

Just to try and clear up a small point made by Littlemanpoet, that the half-orcs were Uruk-hai. In Robert Fosters Complete Guide to Middle-Earth he writes thus:

Half-orcs Servents of Saruman, used by him as spies and soldiers. They were seemingly the product of a cross between Men and Orcs. Although tall as Men, they were sallow-faced and squint-eyed. The Chief's Men were half-orcs.
The half-orcs (the term is not used in The Lord of the Rings) were definitely not Uruk-hai.

Fosters guide is considered one of the better ones, even by Christopher Tolkien.

In Tylers The Tolkien Companion under the Uruk-hai section he states thus: Saruman himself attempted further genetic experiments with the race of 'Great Orcs'- with singularly unhappy results: creatures known as 'Half-orcs' which were said (by Sarumans enemies) to be the result of cross-breeding between Uruk-hai and certain degenerate Men in his service.

It may well be that The Uruks were a cross between Men and Orcs, but they were created by Sauron, not Saruman as it appears in the films. The Uruks first appeared about TA 2475.