Chatham is a term that can refer to several different things.
1) Chatham may refer to an island in New Zealand, known as Chatham Island or Rēkohu in Māori. It is one of the Chatham Islands archipelago and lies about 800 km (500 miles) south-east of mainland New Zealand.
2) Chatham may also refer to a town located on the eastern end of Cape Cod, Massachusetts, United States. The town was named after William Pitt, 1st Earl of Chatham, and is known for its historic lighthouses and fishing industry.
3) In terms of historical contexts, "Chatham" may refer to a specific place or event in the history of the Royal Navy. For instance, HMS Chatham was a name given to several ships of the British Royal Navy, while Chatham Dockyard is one of the oldest naval bases in the world and played an important role during various wars throughout history.
Overall, "Chatham" can refer to different places or events depending on context, but it generally has ties to maritime history or geography.