In 1933, Butler became involved in a controversy known as the Business Plot, when he told a United States congressional committee that a group of wealthy American industrialists were planning a coup d'état to overthrow President Franklin D. Roosevelt.

After retiring from the Marine Corps, Butler became an outspoken critic of American foreign policy and military interventions, which he saw being driven primarily by U.S. business interests.

In 1935, Butler wrote the book War Is a Racket, where he argued that imperialist motivations had been the cause behind several American interventions, many of which he personally participated in.

Using a converted banana boat renamed the Panther, Butler and several hundred Marines landed at the port town of Puerto Cortés.

When they arrived at Trujillo, however, they heard gunfire and came upon a battle in progress that had been ongoing for 55 hours between rebels called Bonillista and Honduran government soldiers at a local fort.

[20] Butler was next assigned to garrison duty in the Philippines, where he once launched a resupply mission across the stormy waters of Subic Bay after his isolated outpost ran out of rations.

On August 11, 1912, he was temporarily detached to command an expeditionary battalion he led in the Battle of Masaya on September 19, 1912, and the bombardment, assault, and capture of Coyotepe Hill, Nicaragua, in October 1912.

[22]Butler and his family were living in Panama in January 1914, when he was ordered to report as the Marine officer of a battleship squadron massing off the coast of Mexico, near Veracruz, to monitor a revolutionary movement.

[28] When President Woodrow Wilson discovered that an arms shipment was about to arrive in Mexico, he sent a contingent of Marines and sailors to Veracruz to intercept it on April 21, 1914.

Following a concentrated drive, several different detachments of Marines gradually closed in on the old French bastion fort in an effort to cut off all avenues of retreat for the Cacos.

[13]Subsequently, as the initial organizer and commanding officer of the Gendarmerie d'Haïti (the native police force), Butler established a record as a capable administrator.

In October 1918, at the age of 37, he was promoted to the rank of brigadier general and placed in command of Camp Pontanezen at Brest, France, a debarkation depot that funneled troops of the American Expeditionary Force to the battlefields.

"[T]he ground under the tents was nothing but mud, [so] he had raided the wharf at Brest of the duckboards no longer needed for the trenches, carted the first one himself up that four-mile hill to the camp, and thus provided something in the way of protection for the men to sleep on.

Confronted with problems of extraordinary magnitude in supervising the reception, entertainment and departure of the large numbers of officers and soldiers passing through this camp, he has solved all with conspicuous success, performing services of the highest character for the American Expeditionary Forces.

Confronted with problems of extraordinary magnitude in supervising the reception, entertainment and departure of large numbers of officers and soldiers passing through the camp, he has solved all with conspicuous success, performing services of the highest character for the American Expeditionary Forces.

[35] Butler won national attention by taking thousands of his men on long field marches (many of which he led from the front) to Gettysburg and other Civil War battle sites, where they conducted large-scale re-enactments before crowds of distinguished spectators.

[35] In 1921, during a training exercise near the Wilderness battlefield in Virginia, he was told by a local farmer that Stonewall Jackson's arm was buried nearby, to which he replied, "Bosh!

[4] He began his new job by assembling all 4,000 of the city police into the Metropolitan Opera House in shifts to introduce himself and inform them that things would change while he was in charge.

Since he had not been given authority to fire corrupt police officers, he switched entire units from one part of the city to another,[3] in order to undermine local protection rackets and profiteering.

More zealous than he was political, he ordered crackdowns on the social elite's favorite hangouts, such as the Ritz-Carlton and the Union League, as well as on drinking establishments that served the working class.

Not all of the citizens felt that Butler was doing a bad job, though, and when the news started to leak that he would be leaving, people began to gather at the Academy of Music.

While there, he cleverly parlayed his influence among various generals and warlords to the protection of U.S. interests, ultimately winning the public acclaim of contending Chinese leaders.

[3] In 1931, Butler violated diplomatic norms by publicly recounting gossip[49][50] about Benito Mussolini in which the dictator allegedly struck and killed a child with his speeding automobile in a hit-and-run accident.

The Italian government protested and President Hoover, who strongly disliked Butler,[51] forced Secretary of the Navy Charles Francis Adams III to court-martial him.

The outspokenness that characterized his run-ins with the mayor of Philadelphia, the "unreliability" mentioned by his superiors when they were opposing Butler's posting to the Western Front, and his comments about Benito Mussolini resurfaced.

[61] After his retirement and later years, Butler became widely known for his outspoken lectures against war profiteering, U.S. military adventurism, and what he viewed as nascent fascism in the United States.

In his speeches he denounced the Economy Act of 1933, called on veterans to organize politically to win their benefits, and condemned the FDR administration for its ties to big business.

The New York Times reported that Butler had told friends that General Hugh S. Johnson, former head of the National Recovery Administration, was to be installed as dictator, and that the J.P. Morgan banking firm was behind the plot.

[76] When the committee's final report was released, the Times said the committee "purported to report that a two-month investigation had convinced it that General Butler's story of a Fascist march on Washington was alarmingly true" and "... also alleged that definite proof had been found that the much publicized Fascist march on Washington, which was to have been led by Major Gen. Smedley D. Butler, retired, according to testimony at a hearing, was actually contemplated".

[79] The funeral was held at his home, attended by friends and family as well as several politicians, members of the Philadelphia police force, and officers of the Marine Corps.