Possible Clues:

• Nationality of citizens of Riga
• Riga residents
• Europeans in surprisingly valiant struggle initially
• Eg, Riga natives
• They come from Riga, say
• Riga natives?
• Europeans use a box, having nails scattered around
• Natives of Riga, say
• Inhabitants of Riga, perhaps
• People whose capital is held by brigands