Blazon: Argent within a bordure gules charged with seven castles or, five escutcheons in cross azure, on each as many plates in saltire
I do really love the gradual evolution of the Portugese coat of arms; in some ways, that’s a more appealing way to trace a nation’s history than a more-or-less static coat of arms.
The story of the Portugese national arms begins around 1096 when Henry of Burgundy became Henry, Count of Portugal by agreement with his cousin Raymond. Traditionally, his arms are given as argent a cross azure. It’s not wholly clear to me whether these were Henry’s actual arms or a later attribution, since heraldic sources for that era were thin on the ground. Even if it is the latter, I’m willing to cut them a bit of slack on this, since it’s such a neat visual predecessor to the current arms. The cross turned into five escutcheons semé of plates either in 1139, when Afonso Henriques became Afonso I of Portugal, or shortly thereafter under his son Sancho I.
The bordure gules semé of castles or was added as a mark of cadency when Afonso III contested his brother Sancho II’s claim to the throne. The castles probably referred to the fact that his mother, Urraca, was a daughter of Alfonso VIII of Castile. Apparently Afonso liked the bordure, since he preserved it in his arms when he finally did become king in 1247.
For a brief period of time, the bordure also incorporated crosses flory vert (or one large cross flory vert, interposed between the bordure and the rest of the shield, so the four points of the cross appeared on the bordure) as a nod to John I’s former role as the master of the Order of Aviz. However, John’s great-grandson, John II, made a number of changes to the royal arms, including removing the cross flory, fixing the number of plates on each shield at five, positioned in saltire, and the number of castles on the bordure at seven.
Somewhat unusually, the arms have remained unchanged since then (mercifully escaping the visual scourge that was the Napoleonic era in heraldry). While the crest, supporter(s), and motto shifted from time to time, the escutcheon itself had basically reached its modern form, and the arms were readopted with a virtually identical blazon by the Portugese Republic when it was established in 1911.
And, of course, would they really be national arms if there weren’t a number of just-so stories explaining the purported symbolism of the charges? Depending on who you ask, the escutcheons represent the five wounds of Christ on the cross (head, feet, arms, and heart), Afonso Henriques’ five wounds from the Battle of Ourique, which formed the basis of Portugal’s ascendancy to a kingdom, or the five Muslim kings that were defeated in that battle. (Another legend about the battle claims the crucified Jesus appeared to Afonso before the battle, promising him victory.) The plates are said to symbolize either the silver paid to Judas Iscariot for his betrayal of Jesus – an odd decision for a very Catholic country – the ability of the Portugese kings to coin their own money, or the nails that held the torn scraps of blue leather to Afonso Henriques’ ruined shield after Ourique. Please do note that there is no evidence whatsoever for any of these claims, and I relate them purely for entertainment’s sake.