That didn’t happen.
Here is an example of what DID happen:
“In late 1911 about 800 Moros fled to the old battleground of Bud Dajo to make a stand. Pershings response to this development provides an illuminating contrast with that of Wood in the earlier episode on the mountain. The matter could be ended without bloodshed, Pershing maintained, if Americans were patient. He wrote, It is not my purpose to make any grandstand play here and get a lot of soldiers killed and massacre a lot of Moros, including women and children.
Pershing succeeded in dispersing the Moros on Bud Dajo with few casualties. Acting swiftly before the Moros could gather provisions or construct cottas, his soldiers surrounded the mountain to cut the Moros off from their sources of supply. Cooperative Moro leaders convinced most of the people to leave the mountain and surrender their weapons. Only 12 Moros were killedfar fewer than the 600 lost 5 years previously.”
He didn’t always have the option of working like that,
“Pershings handling of another case of strong resistance resulted in much more bloodshed, however. In 1913 thousands of Moros moved to the fortified crater of Bud Bagsak in eastern Jolo to defy the disarmament policy. Pershing worked diligently to negotiate the Moros departure, and many eventually left the mountain. However, a group of around 500 remained in their stronghold and refused to surrender their weapons. Unwilling to accept such open defiance and under pressure to end the insurgency, Pershing ordered an attack on Bud Bagsak that resulted in the deaths of almost all the Moros who were there, including as many as 50 women and children. The battle of Bud Bagsak was the last major case of Moro resistance to U.S. control.”
http://www.au.af.mil/au/awc/awcgate/milreview/byler.pdf
Yeah, the pig thing is a myth/legend/propaganda.
100,000 Moros alone were killed over ten years, mostly civilians.