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On the sign:
SE A FORÇA FEZ LEVANTAR UM PADRÃO A TIRANIA A RAINHA NESTE DIA CASCAIS O VAI CONSAGRAR
According to the date on the sign, it is the end of the liberal wars (civil war in Portugal), it may be related to the return of Queen Maria II to the throne.
Translation of the text on the sign: IF FORCE MADE UP A PATTERN TO TYRANNY THE QUEEN ON THIS DAY CASCAIS WILL CONSECRATE