Which work by Georges Braque, the founder of French Cubism, has been called the watershed between traditional and modern art?

This one's a little hard. He and Picasso can be compared year on year. Both are artists of that type and that paradigm.

He's better known for "The House of Estac". In the painting, the house and trees are simplified into geometric forms, and he used a unique method to compress the spatial depth of the picture, so that the house in the painting looks like a cardboard box that has been pressed out of shape, which is between flat and three-dimensional effects. However, most of them were imitated by Cézanne, and this stage was also called "Cézanne-style cubism period".

By 1912. Braque began to create collages. One of his masterpieces is "Clarinet" from 1913. Lines and shadows are sketched in pencil around this group of shapes, with just the right amount of objective reality and subjective creation merging inside.

He enlisted in the army in World War I and continued to paint after his discharge. Later, he gradually broke away from the stereotypes of the early Cubism, the geometric language was modified and changed into a more free and light form, the colors are simple and harmonious, the picture is moderately eclectic naturalism, calm, harmonious and beautiful, constituting a new artistic realm.

I hope this helps you~