Internal strife limited the power and expansion of the Brazilian Navy during the late-1800s and the fleet fell largely out of touch with advancements seen in Europe and elsewhere. An naval arms race brewed with neighboring Chile and Argentina which prompted the service to eventually seek out new warships from Europe in response. The Minas Gerais-class, set to number two strong, was ordered and included lead ship Minas Gerais and her sister, the Sao Paulo.
Minas Gerais (also "Minas Geraes") was ordered in 1906 and constructed in Britain by Armstrong Whitworth at Yard No. 791. Her keel was laid down on April 17th, 1907 and the vessel put out to sea on September 10th, 1908. She was formally commissioned on April 18th, 1910. Although originally designed as a predreadnought warship, the vessel evolved to become a full-fledged Dreadnought-type before she set sail. Dreadnoughts were the call-of-the-day thanks to the arrival of HMS Dreadnought of the Royal Navy in 1906 - rewriting the book on warships through an "all-big-gun" armament scheme and reliance on a steam turbine-based propulsion system.
As built, Minas Gerais displaced 21,555 tons under normal loads and up to 23,400 tons under full loads. She held a length of 543 feet with a beam of 83 feet and a draught down to 25 feet. Her propulsion scheme involved 18 x Babcock & Wilcox boiler units feeding Vickers vertical triple expansion steam engines developing 23,500 horsepower to 2 x shafts. Maximum speed in ideal conditions could reach 21 knots with a 12,000 mile operational range.
Armament was led by 12 x 12" (305mm) /45 caliber main guns set across six twin-gunned turrets. A pair was featured fore and aft of the superstructure while the remaining two were offset at midships. Secondary armament was 22 x 4.7" (120mm)/50 caliber guns running along the sides of the warship with limited traversal. There were also 8 x 3-pounder (37mm) guns fitted for close-in work. The vessel did not carry a torpedo-launching capability.
The ship's profile included a twin-funnel approach and single main mast. The bridge was set aft of the second primary turret. The crew numbered 900. Armor protection was 9" at the belt with casemates covered over in 9" of steel. The turrets held up to 12" of armor plating while the conning tower was protected up to 12" as well.
When introduced, Minas Gerais was a respectable warship of the period and marked the first true Dreadnought of note completed for a minor navy. She was part of the "Revolt of the Lash" mutiny that infected the Brazilian Navy in November of 1910. The situation was defused by capitulation of the Brazilian government to the mutineer's demands.
The warship remained in active service when World War 1 (1914-1918) began in the summer of 1914. Brazil maintained its neutrality until October 1917 after one of its merchants was attacked by a German submarine. Minas Gerais was offered to the Royal Navy as part of the Grand Fleet but the Brazilian warship was in no condition to keep pace with the war - it lacked a modern Fire Control System (FCS) and range-finders for accuracy.
Missing out on combat actions in World War 1, the warship was finally modernized some in the United States in the early 1920s. She then served as a show-of-force during the Tenente Revolts. Another mutiny, this one failing, put Minas Gerais in the forefront once more. From 1939 to 1943, the vessel was modernized again though this time in a Rio de Jainero shipyard.
Despite the work to keep her a viable battleship, Minas Gerais was relegated to nothing more than a floating battery for the duration of World War 2 (1939-1945) - she anchored at Salvador as a fixed defensive platform. With her military usefulness all but over after the war ended in 1945, she was decommissioned (May 16th, 1952) and towed to Italy for scrapping (March 1954).