This is written in response to a Quora question, which asks about Robert Mercer's contribution to the development of machine translation technologies. Feel free to vote there for my answer on Quora!
Robert Mercer (Peter Brown and a few other folks) played a pivotal and crucial role in the creation of the first modern translation models. They were able to create the first modern large scale noisy-channel translation system and publish the first paper on the subject. They created a series of IBM Model X models and spearheaded a new research direction (which is huge nowadays).