Complex sentence: One of the series of Black Paintings Goya painted directly onto the walls of his house sometime between 1820 and 1823, it depicts two men fighting one another with cudgels, as they seem to be trapped knee-deep in a quagmire of mud or sand.
Split into simpler sentences: One of the series of Black Paintings Goya painted directly onto the walls of his house sometime between 1820 and 1823, it depicts two men fighting one another with cudgels. Both men desperately rain blows on one another while they are trapped knee-deep in a quagmire of mud or sand.