Flag of the Netherlands is the oldest tricolor flag. It has tri horizontal stripes in red, white, and blue. Variants of this flag have been in use since 1572. In 1932 it was declared as the national flag of the Kingdom of the Netherlands.
First flag of the Netherland looked very different than today’s. In 15th century Netherlands provinces were united under one lord, and when engaged in common endeavors they used banner of the Lord of Burgundy, so-called “Cross of Burgundy”. It had two red knotted branches as saltire on white background. Provinces of the Low Countries led by the Prince of Orange, revolted against King Philip II of Spain. Pro-independence privateers Watergeuzen attacked enemy under orders from the Prince of Orange and under the tricolor flag Orange White Blue. Because of that that flag soon became known as "the Prince's Flag". In 1572 "the Prince's Flag" was officially introduced as the state banner. The is also a theory that "the Prince's Flag" is a variant of a much older Red White Blue flag that goes back to Charlemagne's time, the ninth century. During the 15th century, the three colors were mentioned as the coastal signals of Netherlands coastal areas and maps made in early 16th century put flags with these three colors next to this region. "The Prince's Flag" had three, six or nine horizontal stripes or as rays placed in circle. Paintings from 1630 Show that in time red color replaced orange but not completely - orange flag remained in use with red.
New flag appeared at the end of 18th century, in time of revolution in the Netherlands and their conquest by the French. "Prince's Flag" was forbidden and the orange-white-blue was changed into red-white-blue which suited to French because it looked similar to their flag. In 1796, to the red stripe of the red-white-blue flag was added figure of a Netherlands maiden, with a lion at her feet. That flag is called “Flag of the Batavian Republic” and it length of life of Batavian Republic - 11 years. Emperor Napoleon made his brother Louis Bonaparte a king of Holland. Louis Bonaparte led pro-Dutch policy and respected national sentiments. He brought back old tricolor. Emperor Napoleon didn’t liked idea for Dutch to have too much liberty so he incorporated the Netherlands into the French Empire and replaced their flag with the imperial emblems.
The Netherlands regained independence in 1813 and Prince of Orange returned to country. From that moment both flags (red and orange) flew together but nether were official national flag. February 19, 1937, a Royal Decree was issued that ordered that red, white and blue flag is national flag of the Kingdom of the Netherlands. It is flown at government buildings and military bases during the whole year. Flag does not have too widespread private use except in case of public holydays such is on Koninginnedag (Queen's Day) when on flag is added orange pennant . One more case is at houses of students who have just graduated.