I'm going to suggest the opium wars (probably the second one 1856 -60 given the look of the uniforms) These were fought between the west and Chinese Qing Dynasty. Mainly over trade rights, but combined with economic disruption in China caused, at least in part, by Britain exporting Opium from India to China (which had been going on since the 1700's, but increased around 1820) Came to head when the Chinese destroyed large quantities of Opium stored in Canton and British sailors killed a local villager.
Could be the scene represents the siege of Canton (which was captured quickly early in the second war)
Hope that helps
Paul