The war that the thing had with the humans. What did they use since there was no bombs or lasers.
They used the powers of hope and love.
A Wrinkle in Timw
Meg confronts IT face to face, and, using the only power that IT does not have - love - is finally able to defeat it. IT only wields the power of hate, and almost overtakes her, but Meg's love for her brother is stronger than the hate of IT. As she and the rescued Charles Wallace embrace, they are tessered back to earth where they are reunited with their family.
http://www.gradesaver.com/a-wrinkle-in-time/study-guide/short-summary/
