"The spring opened ... the colonies, which had now been dissevered from
the British empire, by the declaration of independence"
This is the same spring as in the previous quotation, but if the
Declaration of Independence (July 1776) is in the past, it would have
to be the spring of 1777.
"It was at the latter end of the month of May"
May 1775 or 1777, depending on one's chosen chronology.
"The particulars of this action, in the early stage of the American war,
are yet remembered by many."
The "action" may be a conflation of two different episodes involving
the _Trumbull_, neither of them early in the war: the first was in
June 1780, the second in late August 1781. The _Trumbull_ was towed
to New York, not to London.
"who died there about eighteen months ago"
Alonzo took sail shortly after learning of Melissa's death, so we are
now in early 1783.
[Melissa's gravestone] "October 26, 1776 / In the 18th year of her age."
Depending on the chronology chosen, Melissa's reported death could
have been in 1775, 1777 or 1781. Her 18th year is properly the year
_leading up to_ her 18th birthday, but may mean that she was 18 years
old.
"to be opened that night only, with the tragedy of _Gustavus_"
_Gustavus_ was written by Henry Brooke in 1739 and immediately
banned. Its American premiere was in Baltimore on 14 June 1782.
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