This piece is called, Napolean in the Wilderness, and was painted by Max Ernst in 1941.
Max Ernst was a German artist known for his unconscious and dreamlike art. Ernst challenged and attacked the traditions of art to create non narrative master pieces that would in many works sport religious icons and push the boundaries of what art was considered. Ernst was also highly interested in the art of the mentally ill in that it allowed him to access the primal emotions of man. This piece is a beautiful example of Ernst's work. The wildness and use of color and shape shifting is what really jumped out at me.