It's easy to understand why Monroe was more of a national security president than his predecessors. He had fought as a young man in the Revolutionary War and had a very real perspective on the need for the nation to protect itself from foreign invaders.
Adams, Jefferson and Madison had their philosophy and had been the intellectual foundation of the country and it's system of checks and balances and general idea of what it was to be, but Monroe had a personal appreciation for the value of a strong military and the price paid in gold and treasure for becoming embroiled in foreign affairs.
Monroe like most of the Revolutionaries would be something of a radical in his early years and came to strive for security in his later years.
To me, he's immortalized in the painting of Washington Crossing the Delaware (he's holding the flag on the boat going through the icy waters)