Though this article in today’s New York Times relates to items taken in a different war, it raises issues connected to the Boxer Uprising as well:
China is stepping up the pressure on Christie’s auction house to withdraw two bronzes from its sale of Yves Saint Laurent’s vast collection next week in Paris, saying they were looted from the imperial Summer Palace near Beijing nearly 150 years ago.
The two Qing dynasty bronze animal heads, one depicting a rabbit and the other a rat, are believed to have been part of a set comprising 12 animals from the Chinese zodiac that were created for the imperial gardens during the reign of Emperor Qianlong in the 18th century.
China views the relics as a significant part of its cultural heritage and a symbol of how Western powers encroached on the country during the Opium Wars. The relics were displayed as fountainheads at the Old Summer Palace, known in Chinese as Yuanmingyuan, until it was destroyed and sacked by British and French forces in 1860.
At a press briefing in Beijing last week, a spokeswoman for China’s Foreign Ministry said the two bronzes should be returned to China because they had been taken by “invaders.” And a group of Chinese lawyers says it plans to file a lawsuit this week in Paris seeking to halt or disrupt the sale. But Christie’s says the sale is legal and plans to go ahead with the auction on Monday through Wednesday in Paris, where the two bronze items could fetch as much as $10 million to $13 million apiece.
In both Tianjin and Beijing, there was extensive looting in the summer of 1900. As one American Marine remembered:
Soldiers of all nations joined the orgy…Men of the allies staggered through the streets, arms and backs piled high with silks and furs, and brocades, with gold and silver and jewels.
A brisk trade in looted goods broke out, with open air markets buying and selling goods.
This sometimes led to particularly odd moments. American troops began to sport interesting clothing combinations after the capture of Beijing. As one officer remembered:
‘Not a man was completely clad in American uniform. As they lined up for inspection, some of them wore blue or rose Chinese trousers, others mandarin coats, and almost all of them were shod in Chinese silk boots.’ 
In fact, looting was so extensive that at least one nation’s forces organized things systematically. General Alfred Gaselee, the British commander, set up what could only be called a looting process, to try and keep things somewhat under control. A British officer summed up the process (note the exquisite passive voice of the first sentence):
The unavoidable necessity of looting being recognised, organised parties were, for a time, sent out to collect stuff from unoccupied houses, which was sold at auctions under the supervision of a prize committee, the proceeds being afterwards divided among the troops in shares by rank. As far as one could judge, the loot in Peking was of more value from a curio point of view, but of less value intrinsically, than that in Tientsin. Sycee silver there was, no doubt, as I have heard lots was found, but I fancy this was chiefly by the French, the Russians, and the Japanese. Books, records, pictures, ancestral tablets, and such-like matters of interest to the sinologue and the student there were in plenty; but, as those species were rare, I fancy most of these treasures are still there. There are the usual tales of fortunes made and lost over loot in Peking, but these refer mainly to the more astute, who came up later, and did some good “deals.”
Indian soldiers were given a prize share equivalent to a British soldier of one rank lower, while Indian officers were considered as British NCOs. News of the looting was condemned domestically, with the Daily Express of London saying that “‘civilization'” should have “‘the grace to blush.'”  Little, if any, of the looted material, however, was returned to the Chinese.
Interestingly, the Chinese today may be on firmer legal ground demanding the return of looted objects from 1900 than from 1859-60. There was, as far as I know, no international prohibition against looting in the earlier war, while the Hague Convention of 1899 (to which all the western powers in China were signatories) had outlawed the practice.
 R. D. Heinl, Jr., “Hell in China,” Marine Corps Gazette 43, no. 11 (1959): 55-68.
 Diana Preston, “An Ohioan in China: Adna Chaffee and the Boxer Rebellion” in Timeline 19, no. 1 (2002), 32-47.
 A. A. S Barnes, On Active Service With the Chinese Regiment : A Record of the Operations of the First Chinese Regiment in North China From March to October 1902 ed. rev. & enl ed., (London: Grant Richards, 1902), 139.
 Quoted in James Hevia, “Looting and Its Discontents: Moral Discourse and the Plunder of Beijing, 1900-1901,” in Robert Bickers and R.G. Tiedemann, (eds.) The Boxers, China, and the World, (New York: Rowman & Littlefield, 2007), 93-113.