Developing from a small force protecting United States commercial shipping interests in the Pacific waters off South America, North America and Hawaii, and initially lacking United States ports in the Pacific and operating out of storeships that provided naval supplies, while obtaining food and water from local ports of call in the Hawaiian Islands and towns on the Pacific Coast, the squadron eventually expanded its size and reach as US naval power and national interests grew in the 19th and 20th Centuries.

Off the coast of Sumatra on February 7, the American merchant vessel Friendship out of Salem was attacked by Malay natives described as "warrior pirates".

[4] President Andrew Jackson received word of the 'massacre' and ordered Commodore John Downes in USS Potomac to punish the natives for their acts of piracy.

Arriving off Sumatra exactly a year after the Friendship incident, Commodore Downes with just under 300 bluejackets[5] and marines aboard the frigate, attacked Quallah Battoo, the main village of the hostile Malays.

On 11 July the British Royal Navy sloop HMS Juno entered San Francisco Bay, causing Montgomery to alert his defenses.

The large British ship, the 2,600-ton man-of-war HMS Collingwood, flagship of Pacific Station Commander-in-Chief Sir George S. Seymour, also showed up about this time outside Monterey Harbor.

[9] Commodore Robert F. Stockton took over as the senior United States military commander in California in late July 1846; his flagship was the frigate USS Congress.

Fremont's California Battalion members were sworn in and the volunteers paid the regular United States Army salary of $25.00 a month for privates with higher pay for officers.

Cyane transported Fremont and about 160 of his men to the small port of San Diego which was captured on 29 July 1846 without a shot being fired.

Leaving about forty men to garrison San Diego, Fremont continued on to the Pueblo de Los Angeles where on 13 August, with the United States Navy band playing and colors flying, the combined forces of Stockton and Frémont entered the town without a man killed or gun fired.

Commodore Stockton used about 360 marines and bluejacket sailors with four field pieces from Congress in a joint operation with the approximate seventy cavalry troops supplied by United States Army Brigadier General Stephen W. Kearny, who had arrived from New Mexico, and part of Fremont's California Battalion of about 450 men to retake Los Angeles on 10 January 1847.

On January 16, 1847, Commodore Stockton appointed Frémont military governor of U.S. territorial California – a move later contested by General Kearny.

The retired ship of the line USS Independence was brought back into service, cut down and recommissioned as a razee frigate in 1846.

She entered Monterey Bay on 22 January 1847 after a fast 146-day trip around Cape Horn and became the flagship of Commodore William Shubrick, now commanding the Pacific Squadron.

Three private merchant ships, Thomas H Perkins, Loo Choo, and Susan Drew, were chartered, and the sloop USS Preble was assigned convoy detail.

A Mexican campaign to retake the various captured ports resulted in several small battles and at least two sieges occurred in which the Pacific Squadron ships provided support.

Cyane returned to Norfolk on 9 October 1848 to receive the congratulations of the Secretary of the Navy for her significant contributions to American victories in Mexico.

The Treaty of Guadalupe Hidalgo, signed in February 1848 and its subsequent ratification by the United States and Mexican legislatures, marked the end of the Mexican–American War.

The extent of the Pacific Squadron's responsibility was further enlarged in the 1850s when California and Oregon were admitted as U.S. states and Navy bases on the west coast were established.

In July 1870 the pirate ship Forward attacked and captured the Mexican port city of Guaymas, Sonora in the Gulf of California.

The Pacific Squadron, with Rear Admiral Shubrick, was informed of the incident so USS Mohican was sent to destroy the pirate threat.

As result 150 sailors and marines were landed from the American ships plus another seventy to eighty from the British sloop HMS Tenedos.

The riot was mostly quelled by nightfall but an occupation lasted until February 20 by which time negotiations regarding sugar were concluded, the king also allowed the Americans to build their first repair and coaling station in Pearl Harbor.

[15][16] In 1899 another civil war broke out in Samoa between rebels loyal to the Mata'afa Iosefo and federal forces of Malietoa Tanumafili I. Pacific Squadron Rear Admiral Albert Kautz in USS Philadelphia launched an expedition to the island and occupied the capital of Apia on March 14, 1899 after a battle and bombardment at the port city.