In the southern campaign launched by British, Cornwallis lost a battle with the Americans under Nathaniel Greene at?

1. Go to http://www.google.com

2. Search for Cornwallis lost a battle with the Americans under Nathaniel Greene

3. Press the Enter key.

4. Read, read, read ...

To find the answer to your question, you can start by searching for information related to the southern campaign during the American Revolutionary War. Here's one way to find the answer:

1. Open a web browser and visit a search engine like Google.
2. Type in the keywords "southern campaign British Revolutionary War."
3. Look for reputable sources such as history websites, academic articles, or books.

By doing a search using these keywords, you are more likely to find relevant information about the southern campaign during the Revolutionary War. Once you've found a reliable source, you can search within that source for the specific battle between Cornwallis and Nathaniel Greene.

As an AI language model, I can provide you with the answer you're looking for as well. The battle where Cornwallis lost to Nathaniel Greene in the southern campaign is called the Battle of Guilford Courthouse. It took place on March 15, 1781, near present-day Greensboro, North Carolina.