Leonardo's most important work for Duke Ludovico was to make a huge statue of the previous ruler, Francesco Sforza, on horseback. He started with the horse. After studying horses and drawing designs, he made a huge horse of clay. It was called the "Gran Cavallo". It was going to be cast in bronze. It was going to be the biggest bronze horse that had been made for more than a thousand years. Unfortunately, the bronze horse was never made. In 1494, Ludovico gave the bronze to be made into cannons because the French army was invading Milan. The huge clay horse was still standing when the French army invaded again in 1499. This time it was used for target practice and was completely destroyed.