The science fiction novel The Three-Body Problem provides an excellent example.
By capturing the Earth rebels and obtaining their communication records with the Trisolarans, humanity gained two crucial pieces of intelligence:
The Trisolarans use "Sophons" for omnipresent surveillance, monitoring human activities in real-time.
The Trisolarans fear an ordinary man named Luo Ji and have repeatedly sent Earth rebels to assassinate him.
These two pieces of intelligence directly influenced humanity's subsequent strategic deployments, demonstrating the importance of obtaining enemy intelligence from the actions of traitors.