He received his B.A. from Columbia University in 1912 and his M.A. in 1913 .
MacMahon was born in Brooklyn , New York on May 29 , 1890 , the son of Benjamin and Abbie MacMahon .
MacMahon received MacMahon 's B.A. from Columbia University in 1912 and his M.A. in 1913 .
MacMahon was born in Brooklyn , New York on May 29 , 1890 , the son of Benjamin and Abbie MacMahon .