Why use the word "intervene" (which means happen between two things) instead of happen or held?

Intervene in that instance is exactly right, the election would have altered the circumstances, therefore it would have intervened to change the outcome.

1. To come, appear, or lie between two things: You can't see the lake from there because the house intervenes.

2. To come or occur between two periods or points of time: A year intervened between the two dynasties.

3. To occur as an extraneous or unplanned circumstance: He would have his degree by now if his laziness hadn't intervened.

4.

1. To involve oneself in a situation so as to alter or hinder an action or development: "Every gardener faces choices about how and how much to intervene in nature's processes" (Dora Galitzki).

2. To interfere, usually through force or threat of force, in the affairs of another nation.

5. Law. To enter into a suit as a third party for one's own interests.

Read more: http://www.answers.com/topic/intervene

http://legal-dictionary.thefreedictionary.com/inte...

http://research.lawyers.com/glossary/intervene.htm...

Intervene actually means to step in. Example if a teen is using drugs the family has to intervene or step in and help.