The coat of arms of Portugal is Argent, five escutcheons Azure of five besants Argent in saltire 1, 2 and 1 and a bordure Gules seven three-towered castles Or, 3, 2 and 2.
The Royal Arms
For a little three hundred years, Portugal was ruled by princes from the Burgundian House. Alfonso I, who succeeded his father Henry in 1112, accepted the royal title around 1139. We do not know what Henry’s arms looked like. His reign also seemed quite early for the carrying of a coat of arms except that, as a crusader, he could have put a cross on his armor. A coat of arms is attributed to him with a blue cross on a silver field. These arms is, however, only described many centuries after his death for the first time so that there is no certainty about that. 
Charter from 1139 of Alfonso Henriques signed Æ po rt ug al rex.
In the text he calls himself alfonsus portrugalensium rex. (Arquivo da Torre do Tombo).
The same source responsible for the attribution of the arms with the cross to Henry, also reports on two shields that would have been kept in the monastery of the Holy Cross in Coimbra. The first is attributed to Alfonso I and it is depicted in an engraving as a norman shield with damaged upper edge. According to the caption, there would have been nineteen shields on this, of which seventeen remained. Five are in cross form, the two on the sides with the points inwards. Four smaller ones in the four quarters, also with the points to the heart. Finally, the 10 (8) remaining are on the edge of the shield. The shields are each studded with 13 besants (3,3,3,3,1) and further connected by a cord per bordure, per cross and per saltire
The second shield would have belonged to Sancho I. It shows five shields connected by a cord. 
Whether the shields were actually available or this is just a propaganda item, in any case these shields have disappeared and it can no longer be verified whether they were authentic or not.
Notwithstanding, Sancho I’s arms are confirmed by contemporary seal material. A two-sided wax seal has been kept of this monarch on a document dated 1 March 1195. It shows on both sides an elongated shield with round upper corners on which clearly five shields in cruciform form have the same shape as the main shield. Even it remains possible that in the upper corners and in the tip three more such shields have stood. Due to the poor condition in which the seal is, the edge lettering is unreadable. It is also impossible to see whether the plaques are studded with medals or that merely a relief has been applied to them 
Obverse of a wax seal on a document from 1195 of Sanch I for the Alcobaça monastery.
(Arquivo Nacional da Torre do Tombo)
That the shields must have been strewn with pennies is confirmed by the signatures that can be found on a document from the time of Sancho dated 1183.  The mark of King Alfonso I on it, consists of 12 cross-wise placed shields strewn with white dots. The motto "PAX LUX REX LEX" (peace, light, king, law) stands in the quarters of the cross thus formed; description: Alfonsvs Portvgalensivm Rex.
In any case, the signatures indicate that around 1211, the time that the "forgery" would be made, a cross consisting of more than five escutcheons strewn with pennies was accepted as the emblem of the then only a quarter of a century ago deceased ruler. Indeed, this leaves the possibility open for the blazoning of the original coat of arms as "strewn with shields", (possibly concentrically ordered), or "a cross of shields".
No doubt, however, there can be about the image on the seal that hangs from a document of Alfonso II from 1211. On the shield five shields are strewn with pennies cross-wise, the two shields on the sides directing with their points to the middle.  The figure is known as Quinas. Assuming that the shield of Alfonso I and Sancho I had an indeterminate number of shields that were not necessarily placed cross- wise, then the explanation for the cross of shields of Alfonso II can only be found in a reduction to a cross at a time when the political quarrels for the hegemony between emperor and pope necessitated taking sides. It is precisely at this time that arms with a cross, usually in recognition of papal suzerainty, are beginning to appear gradually.
In the course of time, various explanations of the heraldic device have been drawn up, all based on the form of a cross and the number five. For example, in a description he gave of the Portuguese royal coat of arms, Martinus, Bishop of Lisbon, during his visit to the French king Charles V on 14 July 1380, thought that the five shields were inspired by the five wounds in the form of a cross Alfonso I in the Battle of Ourique (1139) would have suffered. 
"Propter quod rex noster facit quinque scuta in modum crucis cum quinque ictibus, in quolibet scuto in asulio, et albo, pro eo uod in bello victorioso in quo obtinyt contra infinotos sarracenos in campo de Eurriqoe inventa sunt in corpore regis quinque ictus in modum crucis". 
Luis Vaz de Camoes gives in his Lusiades (1572) an other explanation. He too makes a connection between the origin of the arms and the Battle of Ourique but gives a more christian turn to the grounds:
"Tres dias o Grao Rei no campo fica,
Aqui junta no branco o escudo ufano,
Que agora esta vitoria certifica,
Cinco escudos azuis esclarecidos,
Em sinal destes cincos Reis vencidos.
E nestes cinco escudos pinta os trinta
Dinheiros por que Deus fora vendido,
Escrevendo a memoria em varia tinta
D'Aquele de Quem foi favorecido.
Em cada um dos cinco, cinco pinta,
Porque assi fica o numero comprido,
Contando duas vezes o do meio,
Dos cinco azuis que em cruz pintando veio." 
These statements have also been transcribed in later literature and sometimes even further intensified. .
The arms with the Bordure Gules
According to a seal from 1248 the coat of arms of Alfonso II was continued unchanged by his son and successor Sancho II. 
The brother and successor of the last, Alfonso III, bore a coat of arms being an increase of that of his brother and father by adding a red bordure, charged with castles. 
These castles are derived from the arms of his grandfather, Alfonso VIII of Castile. The use of castles for difference of the dynastic arms is also found with his French cousins. These were sons of Louis VIII and the older sister of his mother Urraca, Blanche. So, for example, Robert, Count of Artois, bore the French lilies and a red lambel charged with golden castles. Alfonso, Count of Poitou parted of the French lilies and a red, strewn with golden castles. Charles, Count of Anjou, finally, bore France with a red bordure charged with golden castles. 
Wax seal on a document from 1255 issued by Alfonso III to the Alcobaça monastery.
On this two-sided seal the is the oldest representation of the arms with the bordure and castles .
His arms appear in Walford's roll dating from the time before he succeeded his father as the sole ruler in Portugal. It is described there as: "Le Roy de Portugall, gulez poudre turelles d'or un labell d'azure".  After his succession in Portugal, he continued to bear the arms of his father. It is on his seal, the shields on both sides still with the foot to the center and strewn with an indefinite number of besants, the bordure charged with fourteen castles of the Castilian model with three towers. From his time also dates the first image of the arms in color. It is in the role of arms Wijnbergen, which dates from its first reign before 1290. The coat of arms is silver in it with five blue, escutcheons strewn with besants, and a red bordure charged with fourteen three-towered golden castles. 
Later Developments, the Crest.
The Order of Aviso had arisen from a group of high-ranking Portuguese who had formed an army around 1144 to fight the Moors. After conquering Mafra castle in 1162 that they were allowed to keep, King Alfonso, Alfonso turned the group into a spiritual knighthood. It was named after the conquered city of Evora until 1166, when in 1187 it conquered the fortress city of Aviso and received it as a gift. 
From 1482 to 1485, the improvement of the royal arms was on the agenda of the Cortes that had been called by King John II. Eventually it was decided to leave out the cross of the Order of Aviso as a heraldic anomaly in the future. At the same time, the escutcheons on the sides of the quinas were set upright and the number of castles was set at seven.
A crest appears on the arms for the first time in the coat of arms of the herald Gelre.  It is a castle from the bordure of the arms. The arms represented must be attributed to King Ferdinand I (1367-83). 
King John I also introduced a new crest. It occurs for the first time in his coat of arms of the Order of the Golden Fleece, which, however, arose only after the death of John I. It is a golden dragon issuant that can be seen here as the attribute of St. John the Evangelist and thus as an allusion to the name of King John. It is by no means excluded that the crest was taken over from the Castilian House that was extinct in 1367 but which included the grandmother of John I, Beatrix (daughter of King Sancho IV of Castile). Meanwhile, the House of Trastamare, which had come to power in Castile, used the Castle of Castile as a crest. By the way, John I who was also related to the House Aragon, of which King Peter IV (1336-'87) certainly had a dragon issuant as a crest since 1363. Insofar as the Portuguese kings were members of the Order of the Golden Fleece, their arms were also surrounded by the collar of this order. 
The royal arms with the crest still occurred until the middle of the 18th century.
During the rule of the Portuguese kings from the House of Bragança (1640-1853) the arms were usually represented with a royal crown only. In the 19th century the arms are sometimes surrounded by a crowned mantle.
After the death of King Henry, Cardinal of Lisbon, in 1580, the throne was claimed by King Philip II of Spain who was a cousin of the last kings by his mother Isabella of Portugal. After he had taken Portugal, he added the coat of arms of Portugal to his royal coat of arms. Despite the fact that Spanish rule in Portugal ended in 1640, it remained in the Spanish arms until the reign of King Charles III.
An achievement was introduced in the 14th century by adding two angels for supporters. These were replaced by dragons by the House of Brangança in the 17th century.
From then on the achievement consisted of the ancient Portuguese arms covered with a crowned helmet guardant from which rises a green dragon with red wings. Around the shield is a collar to which the star of the Order of Avis hangs. As supporters serve two dragons as in the crest of which the dexter keeps a banner with the quinas, the sinister a banner of castles of the bordure of the shield. In the 19th century the achievement is sometimes surrounded with a crowned mantle.
In the French period, the heir to the throne, John VI, took refuge to the Portuguese colony of Brazil where in 1808 he proclaimed an independent kingdom. When he succeeded his mother in Portugal in 1816, Brazil and Portugal were united in a personal union into a commonwealth named Reino Unido de Portugal, Brasil e Algarves (the Algarve was a kingdom that was always a fief of the Portuguese heir to the throne). The arms of this united kingdom remained the ancient arms of Portugal, crowned with a royal crown but placed on a golden armillary sphere on a blue background. The Armillary-sphere is surrounded by a wreath of olive and oak branches.
Na het uitroepen van de republiek op 5 october 1910 werd in 1911 een nieuwe wapencompositie vastgesteld. Deze bestond uit het oude Portugese wapen dat geplaatst was op een gouden armiliaarsfeer waarachter een rechtopstaande fasces. Rondom de armiliaarsfeer een krans van olijf- en eiketakken. Niet lang daarna verviel de fasces.
With the disintegration of the United Kingdom in 1822, the Armillary-sphere bearing the Portuguese arms also disappeared. Amongst others on coins from the successors of John VI, the coat of arms of Portugal is depicted on a crowned accolad shield surrounded by a wreath of olive and oak branches.
Just a coat of arms only occurs in the time of the House of Saxe-Coburg-Gotha
After the proclamation of the republic on 5 October 1910, a new achievement was adopted in 1911. This consisted of the old Portuguese arms placed on a golden armillary sphere. It symbolized the Portuguese empire as defined in the constitution of 1822:
The Constitution of 29 of Aprtil 1826 stipulates that the territory of the Kingdom of Portugal and Algarves consists of
O seu Território o Reino de Portugal e Algarves, e compreende:
§1.° - Na Europa, o Reino de Portugal, que se compõe das Provinciasd do Minho, Trás-os-Montes, Beira, Estremadura, Alentejo, e Reino do Algarve e das Ilhas Adjacentes, Madeira, Porto e Açores.
§ 2.° - Na África Occidental, Bissau e Cacheu; na Costa da Mina, o Forte de S. João Baptista de Ajudá, Angola, Benguela, e suas dependências, Cabinda e Molembo, as Ilhas de Cabo Verde, e as de S. Tomé e Principe, e suas dependências; na Costa Oriental, Moçambique, Rio Sena, Sofala, Inhambane, Quelimane, e as Ilhas de Cabo Delagado.
§ 3.° - Na Ásia, Salsete, Bardez, Goa, Dão, Diu e os Estabelecimentos de Macau e das Ilhas Solor e Timor.
Which were briefly defined in the constitution of 1911 as the Portuguese territory at at the date of the procla-mation of the Republic:
O território da Nação Portuguese é o existente à data de proclamção da República. 
Even though the Portuguese empire gradually lost all its overseas territories in the 20th century, the last part – Macao - was lost in 1999, this had no consequences for the arms of state in which the Portuguese arms and the symbol for the overseas territories continued to form a whole.
© Hubert de Vries 2019-03-11
 Ascribing the arms with the cross to Henry originates from Faria i Sousa: Epitome de las historias portuguesas. Madrid 1628, p. 348. With the tradition about the coat of arms of the Portuguese rulers was lengthened by about eighty years up to the first autonomous Portuguese ruler. The circumstance that Portugal had been occupied by Spain for 48 years in 1628 should certainly have a connection with this innovation.
) Faria i Sousa, op.cit. 1628, p. 365. Both chields are extensively treated by Pinoteau, Hervé: Un difficile probleme, celui d l'origine des armes de Portugal. In: XV Congreso internacional Geneologia y Heraldica pp. 377-406, on which this passage is mainly based. The idea of the shields of thenshilds in the monastery of the Holy Cross in Coimbra is copied from Caetano de Sousa: Historia general da casa real portugues. 1735, who gives pictures of the shields of which even every appearance of authenticity is avoided. The shields have continued to haunt in the literature about the emergence of Portugal's arms, with the authors uncritically copying each other.
) Seal of Sancho I on a document confirming the gift to the Alcobaça monastery, dd. 1 maart 1195. Coleccao Especial, c. 28 no 7, Arquivo Nacional da Torre do Tombo, Lisboa.
) This drawn stamp ("sinai rodado") is treated by Mattos, Armando de: Evoluçao historica das armas nacionais portuguesas. Porto, 1939, p 47.. Pinoteau concludes from this that the document, dated February 1183 and which concerns a gift to the monastery Alcobaça, is a forgery made by the scriptorium of the monastery of the Holy Cross in Coimbra and must date from after 6 April 1211 .
) Seal of Alfonso II on a document confriming the gift of Alfonso I to Bernardo, abbot of Claraval. 1211. Arquivo Nacional da Torre do Tombo, Lisboa.
 This was in the same time that the number of fleurs de lis of the coat of arms of France was reduced to three to symbolize the holy Trinity. (1378)
) Bibliotheque de l'Ecole des Chartes, 1891, pp. 499, 516: two manuscripts preserved in the Vatican Library and cited by Gama Barros in his Historia da Administracoa Publica. Dl. III, p. 873, 1st ed.
) In Penguin Classics op p. 86 translated as : “The triumphant Portuguese gathered in the spoils and trophies, and Afonso tarried for the customary three days on the field. It was there that, in token of the victory, he proudly adorned his white buckler with the design of five shields in bright blue, signifying the five kings he had vanquished. And within the five shields, disposed in the form of a cross, he commemorated further the divine help he had been vouchsafed by depicting in a different colour the thirty pieces of silver for which Christ was betrayed, five in each shield, the shield in the centre counting twice.”
) I.c. by Faria de Sousa op.cit. 1628 en Caetano de Sousa, op.cit. 1735.
) Seal on the will of Sancho II dd. Toledo, 3 March 1248. Arms: five eschutcheons strewn with besants cross wise the two on the side with points inwards. (Coleção Especial, c. 28, no 54, Arquivo Nacional da Torre do Tombo, Lisboa).
) Seal of Alfonso III dd. 2 juli 1259: Arms: Five escutcheons crosswise strewn with besants and a bordure charged with eight castles (Colecção Especial, c. 29, no 51, Arquivo Nacional da Torre do Tombo, Lisboa); and a round seal on his will dd. 1271: Arms: Five escutcheosn cross wise charged with 6 besants 2,1,2,1 and a bordure with 12 castles. (Colecção Especial, c. 29, no 51, Arquivo Especial da Torre do Tombo, Lisboa).
) See the articles about Artois, Poitou and Anjou.
) Brault, G.J. op.cit. C 18, Cl 126, Cd 137: Red, strewn with golden towers a blue label. The blasoning of the two other versions not really different.
) Adam-Even, Paul & Léon Jéquier: Un Armorial français du XIIIe siecle, l'armorial Wijnbergen. impr. Lausanne, 1955 (print from Archives Héraldiques Suisses, 1951-'54, p. 74, no 1264. le Roy.de portigal. – D’argent à 5 écus d’azur en sautoir appointés en abîme, chargé de besants d’or; à la bordure de gueules chargée de 14 châteaux à 3 tours d’or. On every escutcheon 10 besants 3,2,3,2.
) Gritzner, M.: Handbuch der Ritter- und Verdienstorden. Leipzig, 1893.
) Brussel K.B. Ms. 15652-56 fol. 167.
)That this is so is proved by a more accurate consideration of the image at Gelre. Here the bordure of the coat of arms on which the castle stands as a crest, is clearly later painted over with the lilies of the cross of Avis which, to our knowledge, can only have been introduced by John I. Stamps of Peter I and Ferdinand I with the castle as crests are not known. It is unlikely that with the arms the arms of John of Castile is meant. At that time he was King of Castile and his arms are depicted elsewhere in Gelre
er I en Ferdinand I met het kasteel als helmteken zijn niet bekend. Het is onwaarschijnlijk dat met het wapen het wapen van Jan van Castilië is bedoeld. Hij was toendertijd Koning van Castilië en zijn wapen staat elders bij Gelre afgebeeld.
) Manuel I, knight no. 144 (1516), John III, knight no. 168 (1531).