As a baby he was given away by his parents and brought up by a laundress. At the age of fifteen he was earning a living by coaching in mathematics. In 1919 he was appointed as a lecturer at U Lviv, Ukraine, and was awarded his doctorate despite having no previous degree. He was imprisoned in L’viv during the Second World War and died shortly afterwards from his consequent ill-health.
http://www-history.mcs.st-andrews.ac.uk/Biographies/Banach.html Fuller biography and photograph.