The first Spanish explorers laid the foundation for our present-day "geographical knowledge of the coasts and interior" of what today is the United States, Larrua said during Thursday's presentation of part one of his three-volume "Historia de la Florida Colonial Hispana (History of Spanish Colonial Florida).

The work was published by the España-Florida 500 Years Foundation in association with Santillana USA and the Spanish Agency for International Cooperation.

"The colonization of Florida was the most difficult that the Spanish undertook anywhere," Larrua says, not only because of the swampy, uncultivable terrain but also due to the numerous enemies they faced - the French, English, pirates, corsairs and very hostile Indian tribes."

This first volume, which covers the 1500-1616 period, incorporates previously unpublished documents pertaining to the exploration of those lands and the massive civilizing and evangelizing effort by Dominican, Jesuit and, above all, Franciscan missionaries.

Larrua used some 130,000 digital images and original documents belonging to the historical archives of St. Augustine, Florida, "which were moved to Havana in 1838."

Between 1565 and 1800, the Franciscans erected 128 missions throughout Florida, lived alongside Native Americans and encouraged them to transition from nomadism to settled agriculture. They also gave catechism classes in the main Indian dialects and taught the local inhabitants basic farming techniques.

The Spanish colonizers treated the Indians more humanely than did the French or English settlers, Larrua said, noting that they believed in reaching across the cultural divide to "work with the Indians and teach them to harvest" crops.

He also cites the 1738 construction near St. Augustine of Gracia Real de Santa Teresa de Mose, or Fort Mose, the first settlement of free blacks in North America, "more than a century before Abraham Lincoln would emancipate the slaves of African descent."

"Other colonizers simply crushed the Indians," he said, contrasting the Spaniards' evangelizing and colonizing efforts with the treatment of the indigenous people in other territories of the present-day United States.

According to Larrua, the Spaniards' greatest achievement was maintaining a chain of religious missions originally set up as part of a "seemingly impossible colonization effort."

Evidence of the integration and assimilation of Indian converts to Christianity can be seen in their massive exodus to Havana in 1763 when Spain temporarily ceded Florida to Britain.

Florida, a vast, imprecisely marked territory that stretched far north of the present-day state's borders, was key to the geopolitical and economic interests of Spain, which "could not lose control of the Florida Straits and the Bahama canal," a natural navigation route for Spanish ships traveling to the Iberian peninsula.

The Spaniards' lasting historical and cultural legacy can be seen today in St. Augustine, the oldest continuously inhabited city in what is today the United States.

Larrua says that when Spain definitively ceded Florida to the United States in 1821 St. Augustine's inhabitants - protected from invasion since the late 17th century by the impenetrable Castillo de San Marcos fort - cursed a treaty that forced surrender upon a colony "that had never bowed down to the enemy."