Complex sentence: The Irish were held as hostages for approximately one month, in an effort to extort terms of ceasefire that were embarrassing to the UN, while the Katangese and their mercenary allies bartered them for prisoners in the custody of the Congolese government of Joseph Kasa-Vubu.
Split into simpler sentences: The Irish were held as hostages for approximately one month, in an effort to extort terms of ceasefire that were embarrassing to the UN. The Katangese and their mercenary allies bartered the Irish soldiers for prisoners in the custody of the Congolese government of Joseph Kasa-Vubu.