In this sentence, I understand that "the leader of its own fascist party" is an appositive phrase (clause?) that identifies "Joseph Phillips." It seems that the next phrase "in the cabinet" is a prepositional phrase. I take grammar tests online and when there is a sentence with a 4-word prepositional phrase, I don't use a comma because I've read that prepositional phrases should have commas only when they have more than 4 words. On this particular site, commas were used with this sentence which has less than 4 four words. If "in the cabinet" is a prepositional phrase, then the commas must be optional. Is that true?
The country that has Joseph Phillips, the leader of its own fascist party, in the cabinet, that sent George Beensly to jail.