The ships were designed to operate on rivers against both air and ground targets, emphasizing shallow draft and a significant number of deck guns at the expense of armor and mobility.

The gunboat had a length of 71.2 m and a width of 10.5 m. An important design feature was the shallow draft of the hull, which was 4.4 m high.

On the return journey, Paraguay ran aground at Piquente Cambá, but it managed to free itself without damage after 28 days.

Ships departed from Asunción loaded with soldiers and equipment to Puerto Casado, from where reinforcements reached the front by trucks or continued their journey by river to Bahía Negra.

In 4 months and 17 days, it made ten trips, transporting 10,301 soldiers and 160 tons of other cargo to the front and bringing 2,009 Paraguayans and 188 Bolivian prisoners to the capital.

According to official data, the gunboat made a total of 81 trips on the Paraguay River, transporting 51,867 soldiers to Puerto Casado.

Initially, the navy supported forces loyal to the president, but when the situation turned against him, the highest commanders declared Ayala their prisoner.

The rebellion also spread to the ships stationed in Argentina – on May 7, supporters of the Febreristas arrested government-loyal crew members on Paraguay, resulting in 4 injuries.

[f] The ships began their journey to Paraguay via the Paraná River on July 5, crossing the Paraguayan border at Paso de Patria five days later.

Humaitá was hit by an aerial bomb the day before and ran aground near the Argentine city of Ituzaingó on July 12.

Uninvolved ships Capitán Cabral and Mariscal Estigarribia and steamers Helen Gunther and Tirador arrived at the gunboats' location on July 15.

Rising river levels allowed the gunboats to attempt a breakout, but it was thwarted by Alfredo Stroessner's forces.

During this time, Paraguay was in Buenos Aires, and Perón took refuge on the Paraguayan gunboat until he was flown to Asunción on October 2.

[23] The ship, equipped with radar and additional anti-aircraft artillery, suffered a bow boiler fire the same year.

[23] Due to the damage, the ship was decommissioned as a combat vessel in 1972 and repurposed for representational and training functions as a stationary unit (hulk).