The Houthis have carried out a lightning advance, catching Saudi-backed government forces off guard in Yemen in September. The Iran-backed rebels swept along the west coast of the country taking control of the Bab al-Mandab Strait, a key maritime corridor. Since then, Yemen’s pro-government forces have managed to retake territory. The BBC's Orla Guerin travelled with pro-government forces through the desert battlefield. Tap the link in @BBCNews’s bio to find out more. #BBCNews