Conversation so far:
What was the relation between Thomas Mitchell and Fourth expedtition?
Mitchell's fourth expedition was into Queensland in 1845-46.
He was convinced that a significant river must flow north-west into the Gulf of Carpentaria.
Where did the fourth expedition take place?
Mitchell started from Boree (Buree in Mitchell's journal) with a large party including Edmund Kennedy as second in command.
Which other people were there with him?
Kennedy was left in charge of the main body here, and was instructed to follow on slowly while Mitchell pushed ahead with a few men.

Question: Do they face any difficulty on their way?
Self-contained rewrite: Do Thomas Mitchell and Kennedy face any difficulty on their way during the fourth expedition?