Owing to the great strength of the island, he was obliged to resort to a blockade, and after a siege lasting nearly two years, the garrison were compelled by famine to surrender in September 1800. Thereafter the island remained an important part of the British Empire until it achieved independence in 1964. Colonel Graham's services were very shabbily acknowledged by the Government of that day, who reserved their patronage and honours for the officers belonging to their own political party.