What is an example of article 4 section 4 of the constitution in history?

In Article 4 Section 4 the United States shall guarantee to every State in the Union a Republican Form of Government, and shall protect each of them against invasion and on Application of the Legislature, or of the Executive (when legislature cannot be convened) against domestic Violence.

supplies had to travel a long distance across water on ships that were often attacked, so they did not reach europe

i believe it to be a democracy