The period from 1811 to 1820 was marked by significant artistic developments and shifts in the art world. Here are some notable occurrences and trends during this decade:

1. Romanticism: The Romantic movement continued to flourish during this period, emphasizing emotions, imagination, and the individual experience. Artists explored themes such as nature, the sublime, mythology, and the supernatural. Romantic painters often depicted turbulent and dramatic scenes, focusing on intense emotions and personal expression.

2. J.M.W. Turner: The British painter J.M.W. Turner emerged as a leading figure in Romantic landscape painting. His works captured the power and beauty of nature, often characterized by swirling brushstrokes, dramatic lighting, and atmospheric effects. Turner's later works experimented with abstraction and influenced the development of Impressionism.

3. John Constable: The English painter John Constable continued to produce his renowned landscape paintings during this period. His works depicted the English countryside with great attention to detail and a focus on capturing the transient effects of light and weather. Constable's paintings celebrated rural life and emphasized the beauty of the natural world.

4. The Hudson River School: In the United States, the Hudson River School of landscape painting emerged during this time. Artists associated with this movement, such as Thomas Cole and Asher B. Durand, focused on depicting the American wilderness, particularly the Hudson River Valley. Their works often portrayed grand vistas, sublime landscapes, and a sense of national identity.

5. Spanish Romanticism: In Spain, the art world was influenced by the political and social context of the time. Francisco Goya continued to produce powerful and introspective works, such as his "Black Paintings," which reflected the turmoil of the Napoleonic Wars and the Spanish War of Independence.

6. Orientalism: Orientalism, a fascination with Eastern cultures and exoticism, gained popularity during this period. Artists sought inspiration from the Middle East, North Africa, and Asia, depicting scenes, costumes, and customs from these regions. Orientalist paintings often portrayed romanticized and sometimes stereotypical images of the "East."

7. Rise of Lithography: Lithography, a new printmaking technique, gained popularity during this decade. Lithographs allowed for mass reproduction of artworks, making art more accessible to a broader audience. Artists such as Francisco Goya and Théodore Géricault used lithography to create prints of their works.

8. Salon Exhibitions: The French Academy's Salon continued to be a significant event in the art world during this period. The Salon provided a platform for artists to showcase their works and gain recognition. The exhibition influenced artistic trends and shaped public taste.

These are some of the notable trends and events that shaped the art world between 1811 and 1820. The period witnessed the continued dominance of Romanticism, the rise of landscape painting, the exploration of Orientalist themes, and the emergence of new artistic techniques like lithography.