This one was a huge canvas !!!!
It's John Martin's painting of Hell called Pandemonium done about 1825. He was inspired by Milton's Paradise Lost and the Book of Revelations for a lot of his works.
In the detail of the painting there are zillions of evil soldiers marching up out of the lava. It's impossible to see that here, and hard to even see it in the huge original with your eyeballs as close as you can get before the museum guards beat you away with a stick, the detail of the soldiers is all so very very very very very tiny in the painting.
(bring your opera glasses)