Definitions of intervene:

• verb:   get involved, so as to alter or hinder an action, or through force or threat of force

  Example: "Why did the U.S. not intervene earlier in WW II?"

• verb:   be placed or located between other things or extend between spaces and events

  Example: "This interludes intervenes between the two movements"

• verb:   occur between other event or between certain points of time

  Example: "The war intervened between the birth of her two children"