Yomp is Royal Marines slang describing a long-distance march carrying full kit. The origin of the word is unclear (one suggestion would interpret it as an acronym of Your Own Marching Pace). It was popularized by journalistic coverage in 1982 during the Falklands War. It has been compared to the term yump used in rally-driving in the sense of `to....
to carry heavy equipment over difficult terrain
[Naval Acronyms and Slang] To force march with a heavy load
Yomp is slang for to walk hard and with vigour.