Chandragupta has founded the Maurya Empire and built a large empire in ancient India. Magadha was an ancient India kingdom and it was ruled by the evil dynasty Nanda.
Chandragupta defeated the Magadha kingdom at first by plundering their villages located near borders and then he was defeated in Nanda's capital city.
The second strategy didn't work either so the third one was to slowly establish the garrisons in territories. His third strategy did work and he killed the king Dhana Nanda.