Why did harry Morgan play 2 different characters in MASH?

Harry Morgan played two different characters in "MAS*H" because he originally portrayed Colonel Sherman Potter, who became a main character in the series starting in its fourth season. Prior to that, he appeared as a different character, Major General Charles Winchester III, in the show's earlier seasons. The decision to cast him as Potter was due to his strong performance and the need for a new commanding officer after the departure of the previous character, Colonel Blake. Morgan's versatility allowed him to successfully transition into this iconic role.