The first bourgeois revolution
Due to complex medieval heritage allignements, in XVI century Netherlands was a part of the domain of Spanish Habsburg dynasty. One can hardly imagine a worse coincidence: the mostly advanced and developped market of Europe was a part of the most backwarded monarchy. Netherlands had many proggressive political achievements, such as large autonomy of provincies and cities, comparably free economy, strong city bourgeoisie, weak nobility and aristocracy, and highly developped political thought (focused on humanism and tolerance). Spain was extremely reactionary, fundamentally catholic, with weak bourgeoisie and strong feudal institutions, and - above all - it was an absolute monarchy with no place for tolerance, autonomy or humanism.
The conflict was amplified by the burst of Reformation in Europe. In 1520s the flame of reform arrived to Netherlands. Reformation steadily gained universal support, regardless of all cruel reppressions. However, the new Spanish king (since 1555) Philip II was determined to clear all religious dissent in his whole domain. He truly hated his Netherland provinces: as a feudal absolutist, he couldn't accept Dutch political institutions, like the parliament (Estates Generales) or local autonomies, and as a fanatically reactionary Catholic, he didn't like the idea of religious tolerance. When his royal governement bankrupted in 1557, he also understood that Netherlands is the richest part of his empire, and tried to tax it as strong as possible.
From the very beginning, the rule of Philip II encountered political resistance in Netherlands. Prince William of Orange and Nassau became the leader of the parliamentary opposition. In 1563 the oppositionists (mainly from aristocracy and nobility) assembled in Brussels and proclaimed their demands. In 1565 the conflict aggravated further, when all members of the opposition resigned from their state posts.
In response, Philip launched a new religious purge by his infamous Spanish Inquisition, resulting in another mass genocide. The people responded with massive uprising - the revolted masses captured such cities, as Maastricht, Valenciennes or Antwerp. The nobility, anxious to cool down the people's rebellion, tried to seek compromise with the Spanish authorities. This allowed Philip to break in blood at first the people, and then the nobility. The opposition was crushed everywhere on Netherland's territory... but it still had one place to hide. It was the sea.
I never heard of any other example of sea guerilla. But it was successful in Netherlands. The ships connecting Madrid with Amsterdam were constantly raided by Dutch pirates - the so called 'gueux de mer'. They supplied themselves in the Hugenot fortress La Rochelle, German port Emden (in Frieslad), and in British ports. On April, 1st of 1572 a fleet of 24 guerilla ships was forced by bad weather to land in a port of Briel. They captured quickly the city with popular support, and Briel was thus the first liberated part of Dutch teritory.
This did not end the whole war. Dutch social fabric was too complex. The nobility, the bourgeoisie and the people had completely different objectives, and fought each other even more often, than the Spaniards. However, the nobility was almost completely disintegrated during various battles. The revolution slowly gained more popular and more bourgeois character. In 1579 the revolted provinces united in Utrecht, creating a new state: The United Provinces of Netherlands. The revolution ended, but the war between Netherlands and Spain still went on. The Spaniards signed ceasefire as late as in 1609, thus officially acknowledging the new republic.
Netherlands became a republic almost incidentally. They simply could not find a good monarch, and therefore they were endlessly ruled by provisional regent (stadhouder). The regency was hereditary for the William of Orange family, but the staadhouder had no real authority over the autonomous provinces. But Netherlands was not a democratic state, neither - the power belonged to bourgeois oligarchy. The best state form to develop capitalism ;-). The oligarchy was also unable to reform itself, what led the state into degeneration in late XVII century. The Dutch revolution was the first large-scale takeover of power by bourgeoisie, and as such it was studied carefully by British, French and American revolutionists.