Answer :
After the death of Marcus Aurelius, the Roman empire slowly started to decline. Potential new emperors began to focus on pleasing the rich Patricians at the expense of the poor plebeians . The resulting decadence was just one reason for the fall of the empire.
(It needs to be pointed out that as the question seems incomplete and lacks more context, the answer might not meet the its standards).
Blank 1 is Marcus
Blank 2 is Military
Blank 3 is People
Blank 4 is Economic
I took the quick check. It was correct.