Alonso Perez du Guzman, the son of the 6th Duke of Medina Sidonia, was born in Spain in 1550. He came from one of the wealthiest families in Spain and was appointed captain general of Andalusia. After the death of his father he became the richest feudal landowner in Spain.

He served in several military campaigns and Philip II considered him the best administrator in the country. In 1586 the king placed him in charge of preparing the invasion of England. After the death of Alvaro de Bazan, the Marques de Santa Cruz in 1588, the Duke of Medina Sidonia was given command of the Spanish Armada.

In July 1588 the Duke of Medina Sidonia and 131 ships left Spain. The large Spanish galleons were filled with 17,000 well-armed soldiers and 180 Catholic priests. The plan was to sail to Dunkirk in France where the Armada would pick up another 16,000 Spanish soldiers that were under the command of Alessandro Farnese, the Duke of Parma.

Charles Howard of Effingham, Lord High Admiral, decided that the Spanish Armada should be attacked at both ends of the crescent. The Ark Royal attacked the right wing and the Revenge and the Triumph attacked Juan Martinez, de Recalde, commander of the Biscayan squadron on the left. Recalde on board the San Juan de Portugal decided to come out and fight the English ships. He was followed by Gran Grin and the two ships soon got into trouble and had to be rescued by the Duke of Medina Sidonia on board the San Martin.

At the end of the first day's fighting, only one ship was sunk. This was Spain's San Salvador when a tremendous explosion tore out its stern castle and killed 200 members of the crew. It was later discovered that a gunner's carelessness resulted in a spark reaching the gunpowder in the rear hold.

The following morning Francis Drake and the crew of Revenge captured the crippled Rosario. This included Admiral Pedro de Vales and all his crew. Drake also found 55,000 gold ducats on board. That afternoon Medina Sidonia announced that if any Spanish ship broke formation the captain would be hanged immediately. He also told his captains that they must maintain a tight formation in order to prevent further attacks from the English ships. This decision meant that they could only move towards Dunkirk at the speed of the slowest ship.

Constantly harassed by the English ships the slow moving Spanish Armada eventually reached Calais without further loss. The English fleet now dropped anchor half a mile away. Soon afterwards they were joined by Lord Henry Seymour and his squadron of ships that had been controlling the seas off Dunkirk. This increased the English fleet by a third and was now similar in size to that of the Spanish fleet.

Medina Sidonia now sent a message to the Duke of Parma in Dunkirk: "I am anchored here two leagues from Calais with the enemy's fleet on my flank. They can cannonade me whenever they like, and I shall be unable to do them much harm in return." He asked Parma to send fifty ships to help him break out of Calais. Parma was unable to help as he had less than twenty ships and most of those were not yet ready to sail.

That night Medina Sidonia sent out a warning to his captains that he expected a fire-ship attack. This tactic had been successfully used by Francis Drake in Cadiz in 1587 and the fresh breeze blowing steadily from the English fleet towards Calais, meant the conditions were ideal for such an attack. He warned his captains not to panic and not to head out to the open sea. Medina Sidonia confidently told them that his patrol boats would be able to protect them from any fire-ship attack that took place.

Medina Sidonia had rightly calculated what would happen. Charles Howard and Francis Drake were already organizing the fire-ship attack. It was decided to use eight fairly large ships for the operation. All the masts and rigging were tarred and all the guns were left on board and were primed to go off of their own accord when the fire reached them. John Young, one of Drake's men, was put in charge of the fire-ships.

Soon after midnight the eight ships were set fire to and sent on their way. The Spaniards were shocked by the size of the vessels. Nor had they expected the English to use as many as eight ships. The Spanish patrol ships were unable to act fast enough to deal with the problem. The Spanish captains also began to panic when the guns began exploding. They believed that the English were using hell-burners (ships crammed with gunpowder). This tactic had been used against the Spanish in 1585 during the siege of Antwerp when over a thousand men had been killed by exploding ships.

The fire-ships did not in fact cause any material damage to the Spanish ships at all. They drifted until they reached the beach where they continued to burn until the fire reached the water line. Medina Sidonia, on board the San Martin, had remained near his original anchorage. However, only a few captains had followed his orders and the vast majority had broken formation and sailed into the open sea.

At first light Medina Sidonia and his six remaining ships left Calais and attempted to catch up with the 130 ships strung out eastwards towards the Dunkirk sandbanks. Some Spanish ships had already been reached by the English fleet and were under heavy attack. San Lorenzo, a ship carrying 312 oarsmen, 134 sailors and 235 soldiers, was stranded on the beach and was about to be taken by the English.

With their formation broken, the Spanish ships were easy targets for the English ships loaded with guns that could fire very large cannon balls. The Spanish captains tried to get their ships in close so that their soldiers could board the English vessels. However, the English ships were quicker than the Spanish galleons and were able to keep their distance.

The battle of Gravelines continued all day. One of the most exciting contests was between Francis Drake in the Revenge and Medina Sidonia in the San Martin. Drake's ship was hit several times before being replaced by Thomas Fenner in the Nonpareil and Edmund Sheffield in the White Bear, who continued the fight without success.

All over the area of sea between Gravelines and Dunkirk fights took place between English and Spanish ships. By late afternoon most ships were out of gunpowder. The Duke of Medina Sidonia was now forced to head north with what was left of the Spanish Armada. The English ships did not follow as Charles Howard of Effingham, Lord High Admiral, was convinced that most Spanish ships were so badly damaged they would probably sink before they reached a safe port.

After the Armada rounded Scotland it headed south for home. However, a strong gale drove many of the ships onto the Irish rocks. Thousands of Spaniards drowned and even those who reached land were often killed by English soldiers and settlers. Of the 25,000 men that had set out in the Armada, less than 10,000 arrived home safely.

Alonso Perez du Guzman, the 7th Duke of Medina Sidonia, died in 1615.