The case of the genocide in Rwanda and Burundi offers opportunities for most interesting historical vignettes.
Its remoteness, rapidity of events and decentralised violence posed huge problems.
Eventually, a rapid offensive of Tutsi forces ended the Hutu-driven genocide, while late-arriving French and Belgian intervention forces did much less. They did provide reliable security for Western reporters, though - and thus got the majority of Western news reports. They were eventually able to pretend that Western intervention alone ended the massacres.
One of the interesting questions from Rwanda is about how intervention forces could and should have been organised.
Mercenaries or typical expeditions with a logistics/liaison advance party would have become effective too slowly. Anything but deployment by air would have been too slow. Support forces were largely unnecessary.
My (old) idea on this is that hundreds of autonomous, cooperating platoons may have been quick enough. They could have arrived with light armament and bicycles at airports (after an airborne company would have overrun that airport). Then they would have followed orders to disarm people (including machetes and clubs)*, arrest leaders and occupy radio stations (and turn pro-violence propaganda around). They would have relied on support by nearby other platoons if in trouble or otherwise too weak for their mission).
This would have been an extreme form of Auftragstaktik with a very flat hierarchy and it would have been akin to warband tactics. It would be beyond our capability for political, cultural and doctrinal (indoctrination) reasons, of course.
I suppose every more thorough and more conventional approach would have taken effect slower.
Germany's Bundeswehr displayed a certain degree of willingness to improvise when during the 1997 "Operation Libelle" German Panzergrenadiere (mechanised infantry) were employed as heliborne force during an evacuation action in Albania. The Bundeswehr appears to have recoiled at the thought of future improvisations and for the last about ten years it appears to have adopted a rather American-style thoroughness and clumsiness. I cannot recount how often I saw info on procurement and training being tailored for (specialised on) the ISAF mission with marginal if any usefulness in other missions. It's been very, very often.
It's very fortunate that the Rwandan genocide was extremely unusual. Maybe we are lucky and don't need the capability to master such a challenge at all.
*: A most troublesome aspect is that they couldn't have told the dfifference between the "good" guys with weapons and the "bad guys" with weapons, and enforcing a general disarmament would have provoked desperate resistance by "good guy" RPF forces. A possible solution would have been a cooperation witht he RPF, including a division of the country in a (Northern) part to be saved by RPF and a (Southern) part to be saved by foreign intervention..