August 4, 1964, June 12 was designated the Independence Day
From 1946 to 1961, Independence Day was celebrated on July 4. On May 12, 1962, President Diosdado Macapagal issued Proclamation No. 28, s. 1962, which declared June 12 as Independence Day.
On August 4, 1964, President Diosdado Macapagal signed into law Republic Act No. 4166, which formally designated June 12 of every year as the date on which we celebrate Philippine independence. July 4 in turn has been observed as Republic Day since then.
The date commemorates the anniversary of the Proclamation of Philippine Independence, because the date remains the foundation date for the modern, independent Republic of the Philippines and of our independent nationhood, as recognized by the world community.