In my travels through South America, I frequently came across the symbol below in churches and religious art. Back in Seville, I had seen the same symbol. It's clearly a connection with the Spanish occupation, but what was it?
This intrigued me, and I did some digging to find out the history behind it all.
The shield belongs to the Order of Blessed Virgin Mary of Mercy, otherwise known as Mercedarians after "merced", the Spanish for "mercy".
The Order was founded on August 12, 1218 AD, by Bishop Berenguer de Palou in Barcelona. The driving force behind the Order was Saint Peter Nolasco (1181 - 1245 AD).
The purpose of the Order was to liberate faithful Christians who were held prisoner by the Saracens in the Moorish part of Spain. They did this by raising money to pay the ransom or, in extreme cases by substituting themselves for the prisoner.
The shield is the vertical red and gold bands of the King of Spain at that time, James I, surmounted by the white cross of Barcelona cathedral.
The Order came to the Americas on the second voyage of Columbus in 1493 and also accompanied Pizarro in his conquests.
This is my imperfect understanding of some of the history of the Order, and a much more comprehensive document is displayed at http://www.orderofmercy.org/HistoricalSurvey.htm.