The watercolor medium, as the first truly portable plein air painting medium, has played a seminal but often underappreciated role in the rise of modern painting. Starting with 17th century Holland and concluding at the dawn of the 20th century, a brief historical survey of a small group of artists, from the world-famous to those familiar only to specialists, will illuminate the contributions watercolorists have made in the evolution of landscape art in particular, and modernism overall.