disunite vs factionalize

disunite

verb
  • To separate, sever, or split. 

  • To cause disagreement or alienation among or within. 

  • To disintegrate; to come apart. 

factionalize

verb
  • To split into factions 

How often have the words disunite and factionalize occurred in a corpus of books? (source: Google Ngram Viewer )