The UK deployment to Sierra Leone was not a UN operation, in 2000 the largely African Union manned UN op there seemed in disarray, the country seemingly on the verge of massive human suffering.
It was quite controversial sending UK forces, some on the Tory benches asked 'what's in it for us?' The hard left cried 'Imperialism'.
The situation seemed to stabilize, then came the hostage crisis, the enemy being a drunk and drugged up bunch of thugs called 'The West Side Boys', whose leader made increasingly irrational demands and threats.
So 'Operation Barras' was launched, troops were from one of the battalions deployed in country, 1 PARA, as well as the SAS.
Chinooks provided airflift, Lynx AH
.7's provided fire support and C3
, once the hostages were sprung, a fierce firefight ensued, the WSB being more heavily armed than expected, and too out of their heads to have any idea of self preservation, the UK troops ended up using mortars, around 20 of the WSB were killed, their leader captured, one SAS trooper was killed.
The WSB were finished after that.
This seemed to break the back of the terror in Sierra Leone, eventually a much more robust and successful UN operation largely replaced the UK forces, though some are/were deployed in training the Sierra Leone forces.
Prior to the hostage operation, one insurgent group was found to be prone to dispersal merely by Sea Harrier's from HMS Illustrious flying low over them, with the aircraft not needing to use any ordnance.
An unusual operation, since unlike France, the UK is usually much less keen to get entangled in former African colonies, but the terrible situation for the ordinary people there was heavily featured in the UK media, so Blair put his 'Lord Palmerston' head on (his nickname from the Foreign Office).
By all accounts, many citizens were not happy to see the UK troops leave, even wanting to reverse their 40 years of independence.
A lesson perhaps? UN operations can work, but sometimes the ground has to be prepared by a force not encumbered by the inevitable compromises a multi national UN force might suffer from.