In 1684 he was sent to Bombay by the King of England to put down an insurrection led by the Company, who had set up a parallel government and assumed wide authority on the British people.
After he landed in November 1684, he assumed control over the situation from Commander Keigwin and thus ending the standoff.
Grantham was also responsible for the strengthening of the walls of the Mahim Fort against attacks by the Portuguese who occupied the northern island of Salsette.
Unfortunately, promises of lenient treatment were not honored by Governor Berkeley who had most of the men hanged.
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