We don't have synonyms for long march yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are long mark and long marks.
(n) :
(historical) A military retreat undertaken by the Red Army of the Communist Party of China, the forerunner of the People's Liberation Army, to evade the pursuit of the Kuomintang (KMT or Chinese Nationalist Party) army.
(n) :
(historical) A military retreat undertaken by the Red Army of the Communist Party of China, the forerunner of the People's Liberation Army, to evade the pursuit of the Kuomintang (KMT or Chinese Nationalist Party) army.