From A History of the International Date Line:
European explorers who approached the Pacific Ocean by sailing to the east such as the Portuguese, and in their wake the Dutch, the English and the French, naturally kept their ship’s journals and diaries according to the day count of their home land and this was of course also adopted by the colonists who settled along the Asian perimeter of the Pacific Ocean.
However, the colonisation of the Pacific Ocean by the Spanish occurred from the opposite direction and more specifically from the Spanish possessions in America. The Philippine archipelago was discovered in March 1521 by Ferdinand Magellan and Spanish dominion over the islands was first firmly established in 1565 by Miguel López de Legazpi (c. 1510 – 1572), the conquistador and first Spanish governor general of the Philippines….
Most of the shipping from the Philippines to Spain went over the Pacific Ocean to the Mexican port of Acapulco, was transported over land to the port of Veracruz, and then shipped to Spain. In order that the Spanish ships crossing the Pacific Ocean between the Philippines and the Spanish Americas would not have to adjust the dates in their journals whenever they sighted land, the Philippines observed the same day count as that of the Spanish Americas….
During the early 1840s the commercial interests of the Philippine Islands turned more and more away from the Spanish Americas (which for a large part had severed their relations with the motherland Spain) and trading with the Chinese mainland (engendered by the ignominious but lucrative ‘Opium Wars’), the Malay peninsula, the Dutch East Indies and Australia became increasingly important.
In order to facilitate communication and trading with its western and southern neighbours, the secular and religious authorities of the Philippines agreed that it would be advantageous to abolish the American day reckoning and adopt the Asian day reckoning.
This was achieved in 1844 when Narciso Claveria, the governor general of the Philippines, issued a proclamation announcing that Monday, 30 December 1844, was to be immediately followed by Wednesday, 1 January 1845.
The 1867 conversion from Russian to American time in Alaska was much more complicated.
From Iranun and Balangingi: Globalization, Maritime Raiding and the Birth of Ethnicity, by James Francis Warren (Singapore U. Press, 2002), pp. 345-346, 363-364:
By the first quarter of the nineteenth century, the sea war in the Philippines between Spain and the Iranun and Balangingi had taken on a permanent and normal character of a stalemate in which each party recognized the other as an equal with authority generally limited to the territory each controlled. But in 1848 the combined forces of the Spanish navy and army laid waste to the Samal forts at Balangingi, dispersed the survivors, and forcefully relocated the prisoners of war. This was the decisive moment, the turning point in the history of the century-long conflict between Spain and the slave raiders. The Balangingi were on the brink of climbing out of their Samal identity after nearly half a century of constant upheaval, and, according to Frake, “establishing themselves as a different kind of people.” But, in the aftermath of the Spanish devastation of their island stronghold in 1848, they did not succeed. After that event the Balangingi, as ‘notorious pirates’ and a construed single ethnic group, disappeared from the pages of the historical literature and geographical reports. Balangingi fortunes changed in the 1840s and with them the pattern of maritime raiding in Southeast Asia. The destruction of Tempasuk and Marudu by the English in 1845 also forced Iranun groups to relocate on the east coast at Tunku. The loss of these confederate communities made it more difficult for the Balangingi to conduct slave raids in the western sector of the archipelago. This event, coupled with the founding of Labuan by James Brooke and the appearance of steam gunboats on the northwest coast of Borneo, forced them to gradually withdraw from that area and increasingly concentrate their activities on the Dutch possessions.
At the same time, the Spanish adopted a far more aggressive policy in the south. The new governor of the Philippines, Narciso Claveria, understood the strategic importance of the control of Balangingi which became the focal point of a new Spanish strategy. A daring naval attack aimed at the throat of the Sulu, namely Balangingi, was the key to cutting the sultanate in two and stopping slave raiding in the Philippines….
After the destruction of Balangingi in 1848, the Spanish first used the Samal women and children as hostages to force their husbands and kindred to surrender and make peace. The political ploy did not work. So after a short time, the Spanish assembled their steamers and regularly swept the Visayas and the Sulu archipelago from one end to the other. Repeated punitive campaigns ended with a series of major sea battles off the coasts of Samar and Mindanao and attacks on Taupan’s bases to the south. [Julano Taupan was war leader of the Balangingi at Tawi-Tawi.] Hundreds of Balangingi were killed during the six year long war, many of their ships captured, and others destroyed. Taupan sent his raiders to prey on shipping in less troubled waters in the Moluccas, the Banda Sea, the Java Sea, and along the Bornean coasts. But their activities were short-lived. The British and Dutch dealt with the Balangingi menace by joining forces across the region, stationing steamers in all the key straits of the archipelago at certain times of the year when the slave raiders traditionally appeared in those waters. The Dutch navy concentrated on Taupan’s Balangingi operations around Sulawesi and Bonerate, and the British, with James Brooke’s full support, stationed ships at Labuan to protect the Borneo coasting fleets in the South China Sea.