Why Oliver Cromwell chose Richard as heir

Whom did Oliver Cromwell designate as his heir, and why?

He chose his son Richard because the regime needed a named successor around whom the army could organize.

Oliver Cromwell designated his son Richard as his successor after pressure to provide an heir around whom the army and political system could organize. The choice addressed institutional continuity as much as family preference. Richard's later inability to hold that coalition together helped open the path to the Restoration.