From what I recall, the Irish were dumb enough to sign up for a UN mission in the Congo to support Lumumba because the Katanga providence declared independence. Lumumba was friendly with the Soviets, as an aside. Basically Katanga had a large number of mines run by the Belgians. Their military was largely mercenaries, but with a fairly strong indigenous component. They launched a mission to capture said Irish troops for leverage. The Irish admittedly fought well for 5 days considering they had a bad position, virtually no support, limited supplies, etc. They surrendered when they ran out of ammo. The truly surprising part is that the Irish forces treated mercenary captives well, and the mercenaries treated Irish captives well.
Katangese Gendarmes folded not long afterwards. Honestly the entire campaign did no one much glory. The Irish troops were treated as cowards afterwards, despite the fact that they fought well. By "fought well" they killed 300 enemy forces while suffering 5 wounded. They had only small arms, a couple Vickers and a couple mortars. The other UN forces didn't/couldn't reinforce them, though admittedly they did try. The Katanga forces managed to hold off the reinforcements. It took 40 years for the Irish government to clear their solders' names, after unofficially branding them cowards for that interval.
The UN occupation worked. Even though it was expensive, poorly managed, etc. Worked in that it crushed the rebellion. Congo remained unstable until the CIA put Joseph Mobutu in power four years after the Katanga rebellion. Joseph Mobutu ruled Congo for 30 years and ran it into the ground via corruption, incompetence, poor human rights record and nepotism.
Shorter version: Don't volunteer for UN missions unless you like epic clusters. Even if your troops accomplish an amazing seige, it'll end badly.
