Sailing to Portugal with his stepson Charles Elers Napier as aide-de-camp, bringing troop reinforcements and using the incognito of 'Carlos da Ponza', he arrived in Porto, where Queen Maria's father Dom Pedro, ex-Emperor of Brazil, and the Liberal forces were being besieged by Miguel's armies.
Continuing his Portuguese services, Napier commanded land forces in the successful defence of Lisbon, September 1833.