Book excerpt: Napoleon III's motives for intervening in Mexico in the 1860s were consistent with his foreign policy, which was based on his belief that free trade was the best foundation for peace. He saw the establishment of a friendly government in Mexico as an opportunity to expand that policy to encompass the world by ensuring European access to American markets, and preventing monopoly by the United States. His attempts to achieve this, however, were thwarted by his representatives in Mexico and the suspicions of his neighbours.