Complex sentence: His support for this initiative, in turn, allowed Galtieri to remove a number of rival generals and, in December 1981, he rose to the Presidency of Argentina by means of a coup that ousted General Roberto Viola.
Split into simpler sentences: His support for this initiative allowed Galtieri to remove a number of rival generals. In December 1981, he rose to the Presidency of Argentina via a coup that ousted General Roberto Viola.