Final answer:
Jacques-Louis David was the Neoclassical artist who led the way to revolutions in both art and politics.
Step-by-step explanation:
The Neoclassical artist who paved the way for both art and political revolutions is Jacques-Louis David.
David was trained in classicism but adopted a more severe style called Neo-Classicism. He became the painter of the French Revolution and was involved in its most violent aspects. After the revolution, he served as the official painter for Napoleon Bonaparte.
His influential works, such as the painting Oath of the Horatii, reflected the rationality and sobriety of the Neoclassical movement and supported the rebels in the French Revolution.