Arguably one of the most famous revolts in Philippine history is the Silang Revolt from 1762 to 1763, led by the couple Diego Silang and Gabriela Silang. Unlike the other revolts, this revolt took place during the British invasion of Manila. On December 14, 1762, Diego Silang declared the independence of Ilocandia, naming the state "Free Ilocos" and proclaimed Vigan the capital of this newly independent state. The British heard about this revolt in Manila and even asked the help of Silang in fighting the Spanish. However, Silang was killed on May 28, 1763 by Miguel Vicos, a friend of Silang. The Spanish authorities paid for his murder, leading to his death in the arms of his wife, Gabriela. She continued her husband's struggle, earning the title "Joan of Arc of the Ilocos" because of her many victories in battle. The battles of the Silang revolt are a prime example of the use of divide et impera, since Spanish troops largely used Kapampangan soldiers to fight the Ilocanos. Eventually, the revolt ended with the defeat of the Ilocanos. Gabriela Silang was executed by Spanish authorities in Vigan on September 10, 1763.

Answer this question based on the article: On what 1/12 of a year did Diego Silang declared the independence of Ilocandia?