dash someone's hopes
Destroy someone's plans, disappoint or disillusion. For example, That fall dashed her hopes of a gold medal. This term uses dash in the sense of “destroy,” a usage surviving only in this idiom. [Second half of 1500s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.