Which country's national anthem is an acrostic (the first letter of each verse spells out a name)?

"Wilhelmus van Nassouwe", usually known just as the "Wilhelmus", is the national anthem of the Kingdom of the Netherlands. It dates back to at least 1572, making it the national anthem with the oldest music. Although the "Wilhelmus" was not recognized as the official national anthem until 1932, it has always been popular with parts of the Dutch population and resurfaced on several occasions in the course of Dutch history before gaining its present status. It was also the anthem of the Netherlands Antilles from 1954 to 1964.

The "Wilhelmus" originated in the Dutch Revolt, the nation's struggle to achieve independence from the Spanish Empire. It tells of the Father of the Nation William of Orange who was stadholder in the Netherlands under the King of Spain

The complete text comprises fifteen stanzas. The anthem is an acrostic (a poem or writing in which the first letter of each line spells out a word or message): the first letters of the fifteen stanzas formed the name "Willem van Nassov" a revolutionary hero of the Dutch revolt against Spain.