The 18th Mounted Brigade previously known as the 2/1st Yorkshire Mounted Brigade was a second line yeomanry brigade of the British Army during the First World War. Raised after the declaration of war, it was a mirror formation of the first line Yorkshire Mounted Brigade. It had under command the 2/1st Yorkshire Hussars, the 2/1st Queen's Own Yorkshire Dragoons, and the 2/1st East Riding of Yorkshire Yeomanry. All of which were converted in cyclist units in 1916, the brigade, never having seen any active service, ceased to exist.