In the beginning, there was little order in ship schedules to and from the Indies. As news of rich cargoes spread, appetites were whetted and envy aroused. The Barbary Coast pirates, with long experience in the business, were the first to act. Their large fleets hovered off the Spanish and Portuguese coasts, capturing ship after ship. Pirates of French, English and Dutch descent followed this trend. Such plundering soon provoked near panic in Spain and officials of the Bureau of Trade, which promoted and regulated trade and navigation with the New World, scurried to do something to check the menace. They countered with the formation of what was to become the armada system.
In 1522, the Bureau issued an order stating that no caravels of less than 80 tons were to cross the Atlantic alone and must carry guns. At the same time, the first squadron was formed to patrol the Portuguese coast and escort transports through pirate-infested waters. In 1525, the Council of the Indies was formed to supervise New World trade and it worked out a plan for the convoys. Cargo ships were to cross the Atlantic in fleets of 6 or 10 ships, escorted by four 250 to 300 ton galleons and two 80 ton pataches. A new order in 1537 stipulated that all returning ships had to meet in Santo Domingo and cross in an armada.
The convoy system was further developed in 1543, at which time the Bureau stipulated all Indies trading ships must be of at least 100 tons, and leave Seville in groups of 10 or more, twice yearly (March 1st and September 1st). In 1554, departure dates were changed to a month earlier due to better information relating to hurricanes. In 1565, with the establishment of viceroyalties (provinces) in the New World, the Bureau issued its first comprehensive armada plan.
Two Indies armadas were formed: the New Spain, called "the Flota," and the Tierra Firme, called "the Galleons." This 1565 order was specific. Two fighting galleons, normally the largest and strongest available ships, accompanied each armada. One, designated the Capitana, carried the commanding officer, called the general, who was responsible for safety and welfare, for the guns, charts, soldiers, and adequate provision. The Capitana sailed at the head of the armada. Bringing up the stern was the other galleon, called the Almirantas, which carried the admiral, second in authority. He took command when there was fighting. After several terrible experiences when ships were lost in battle, the result of incompetence, regulations were further tightened, and in 1572, Capitanas and Almirantas were prohibited from carrying any cargo except the king's treasure. As well, they were always required to be ready for battle.