Idiom meaning, usage examples, facts

1. Once you narrow down the topic for your dissertation, that’s half the battle. Doing the research and writing it is the other half.
2. I finally bought all the materials to build those bookshelves. That’s half the battle.

The expression is used to describe what may seem to be less than half the effort, a small part of the effort or just the beginning of the effort, but which in fact goes a long way to getting the work done.