Was gunsmoke's first six seasons called marshall dillon?

No, Gunsmoke's first six seasons were not called "Marshall Dillon." The show aired under the title "Gunsmoke," featuring the character Marshall Matt Dillon, portrayed by James Arness. The series debuted on CBS in 1955 and became one of the longest-running prime-time dramas in television history. The title "Marshall Dillon" is often associated with the character but not as an official title for the show.