Rio de Janeiro Affair The Rio de Janeiro Affair refers to a series of incidents during the Brazilian Naval Revolt in January 1894 . Following three attacks on American merchant ships in the harbour of Rio de Janeiro , a bloodless naval engagement occurred between a United States Navy warship and an ironclad of Rear Admiral Saldanha da Gama ' s rebel fleet . Ultimately the Americans completed their objective , and the Brazilian rebels offered to surrender their ships . Affair . The incidents which led to the short engagement began on January 21 of 1894 , when the 586 ton American bark SS " Julia Rollins " was fired on with rifles from a fort on Cobras Island , while heading to Gamboa . Brazilian fire was heavy though nobody was harmed ; the American crewmen were forced to take cover and maneuver their ship out of the fort ' s range , where they laid anchor . The Brazilians then opened fire again , but this time with the guns of the ironclad cruiser s " Trajano " and " Guanabara " . " Julia Rollins " moved once more until finding a safe anchorage , then a boat with a few sailors was the lowered and sent to inform Admiral Andrew E . K . Benham , who was in command of three cruisers at Rio de Janeiro with orders to protect American interests and observe the rebel blockade . On January 26 , another incident occurred when the bark " Agate " was fired at with rifles and naval guns from Cobras Island and the rebel cruisers . Again nobody was hurt , but Admiral Benham , who was busy communicating with Da Gama , warned him not to attack American vessels . USS " Detroit " , under Commander Willard H . Brownson , was one of the modern cruisers in Benham ' s squadron . The other two were the USS " San Francisco " and USS " Newark " . Admiral Saldanha Da Gama ' s fleet of twenty - four ships was much stronger , as most of the rebel navy was stationed at Rio , though only the " Trajano " , the cruiser " Guanabara " and the gunboat " Liberdade " were directly involved . The 1 , 400 ton " Trajano " was armed with twelve guns and the much larger 2 , 200 ton " Guanabara " mounted eight . " Liberdade " was only 250 tons but armed with eight guns . She was Da Gama ' s flagship and patrolled back and forth between the two cruisers and the main fleet . Brazilian commanders expected a battle against the American squadron so men from other ships were used to reinforce the " Trajano " and the " Guanabara " . The affair climaxed on January 29 when Benham ordered Commander Brownson to escort the American merchantmen into the wharves , where their cargoes would be unloaded , and to attack the first Brazilian ship to open fire . So at 6 : 00 am the " Detroit " headed in , followed by the " Julia Rollins " , the " Agate " and the barks " Amy " and " Good News " . The " Detroit " was cleared for action and at 6 : 20 the crew was at battle stations with guns loaded . But just then , while sailing between Cobras and Enchadas Island , lookouts observed two or three Brazilian auxiliary cruisers which were beginning a bombardment of the federal shore batteries near Santa Barbara Island . Commander Brownson decided to wait for the engagement to end so he did not violate neutrality , and as soon as the armed tugs hauled off the American ships were underway . The " Trajano " and " Guanabara " were not far away , the two cruisers were moored to a buoy in line of battle , and Admiral Da Gama ' s flagship was nowhere in sight . By 7 : 00 am , " Detroit " and her escortees were within gun range of the rebels and at about that time the " Trajano " fired a warning shot over the " Amy " s bow which temporarily stopped her . In order to get the ships moving , Commander Brownson had to assure the merchantmen that he would protect them if there was any more fire . An attack came a few minutes later ; at 7 : 04 the " Amy " received a round from the " Trajano " s naval musket . Immediately " Detroit " returned fire with one of her guns and a shot hit the " Trajano " s stern about two or three feet from the starboard bow , causing light damage . Brownson then hailed the Brazilians , who were less than sixty yards away , and the commander declared that " " If you fire again l will return the fire , and if you persist in firing I will sink you " " . However , " Trajano " s crew opened fire again with a full broadside from the starboard battery ; one near miss went over the " Detroit " and another over the " Amy " but no damage was caused . For the next several moments the " Detroit " maneuvered , and at 7 : 16 am Brownson found himself in a good position to rake the enemy vessels from 200 yards away . That morning the sea was rough , so the anchor was dropped and preparations were made to slip the cable if necessary . The American barks were directed to continue on to the wharves . At 7 : 32 am the " Trajano " fired another broadside at the " Amy " ; all shots missed . USS " Detroit " responded and a second round struck the " Trajano " under the counter , near her sternpost . Following this the rebels ceased firing and the engagement was over , after about a half an hour . Admiral Da Gama only found out that there had been an exchange of fire when he anchored the " Liberdade " and two of the tugs near the " Guanabara " . Captain Brownson sent an officer aboard the " Liberdade " to ensure a ceasefire . Da Gama said that he had not ordered the attacks on the American barks , and that only blank rounds had been used during the first incidents in order to scare off the merchants and not actually harm them ; however minor damage from rifle fire to the " Agate " and the " Julia Rollins " proved otherwise . Da Gama also offerred to surrender his fleet to Admiral Benham , but the offer was not pursued . American reports make no indication of casualties on either side and the affair did not go any further . In the end , " Detroit " successfully reopened Rio to American commerce , and Brownson ' s bold actions are credited with preventing any more attacks on United States flagged ships during the revolt , which ended in March 1894 . The captain became known for the engagement , and newspapers across the United States reported the story .