He gradually rose through the ranks and participated as a lieutenant in the United States military crackdown against strikers in the wake of the Great Railroad Strike of 1877.

He and a small contingent of sailors and marines defended the American consulate in Santiago, Chile during the 1891 Chilean Civil War.

After the war, he was made the first acting-Governor of Tutuila and Manua (later called American Samoa) and set legal and administrative precedents for the new territory.

[3] In July 1877, a violent railroad strike began in Martinsburg, West Virginia, sparking riots in other American cities such as Pittsburgh and Philadelphia, and President Rutherford B. Hayes authorized the use of the military in response.

The troops defending Washington included the army, navy, and marines organized into a battalion of seven companies (Naval Brigade) under the command of Captain Edward Barrett; Tilley was placed in command of Company C. The precautions proved to be unnecessary, as the expected wave of rioters never materialized following the military's suppression of the strikers in Baltimore; the riots were also quashed in other cities within a short time.

On June 6, 1878, he married Emily Edelin Williamson, the daughter of a Navy surgeon, and left with her on an extended honeymoon in Europe.

[8] San Francisco transported troops to the port of Valparaíso during the 1891 Chilean Civil War, from which they could move on to protect the American consulate in the capital of Santiago.

On April 23, 1898, Spain declared war on the United States in response to American efforts to support Cuban independence.

The United States responded with its own declaration of war against Spain on April 25, and Tilley captured the Spanish Navy's sloop Paquete and schooner Pireno two days later.

[17] On February 13, 1878, a separate treaty was ratified by the Senate that granted the Samoan government diplomatic recognition and reaffirmed permission to build a naval station in the country.

The construction of the naval base remained his primary responsibility, and he was dispatched to pick up additional supplies and coal at Auckland, New Zealand.

[19] Tilley's first task in his new role was to negotiate a deed of cession with the local powers to ensure a formal and peaceful transfer of control to the United States.

The inhabitants of the island of Taʻu and the volcanic doublet of Ofu-Olosega (together known as Manu'a) 70 miles (110 km) to the east were politically separate from Tutuila.

Over the next year, Tilley regulated firearms, enforced mandatory registrations of births, deaths, and marriages, levied taxes, and made the sabbath a public holiday.

The native challenged his punishment under the American legal system, however, resulting in the arrest of the chief responsible for ordering the destruction of his property.

The chief was sentenced to a year of house arrest in a criminal proceeding, on which Tilley sat as judge, and he was ordered to pay compensation for the destroyed property.

That month, an anonymous complaint was made to Assistant Secretary of the Navy Frank W. Hackett against Commandant Tilley, alleging immorality and drunkenness.

[26] Unlike Sebree, who was concerned that he did not have a legal mandate to govern, Tilley was not shy about enacting legislation and being the de facto leader of the territory.

Although the deed of cession recognized his authority and gave him the title of Acting Governor, as far as the United States government was concerned, he was officially responsible only for the naval station.

[29] On February 23, 1907, he was made commandant of League Island Naval Yard in Philadelphia, Pennsylvania, and he was promoted to rear admiral the following day.