Among the people on the Second Fleet were D'Arcy Wentworth and his convict mistress Catherine Crowley , on Neptune , and John Macarthur , then a young lieutenant in the New South Wales Corps , and his wife Elizabeth , on Scarborough . Among the arrivals on the Second Fleet were D'Arcy Wentworth and his convict mistress Catherine Crowley , on Neptune , and John Macarthur , then a young lieutenant in the New South Wales Corps , and his wife Elizabeth , on Scarborough .