She should have died hereafter meaning.
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"This line has caused some debate. Four possible meanings are (1) she should have died after the battle when there would be time to mourn properly; (2) she should have waited for me, seeing that my death is so near; (3) she would have died at sometime, either now or later; (4) she should have died after the battle for now, with her gone, I know I shall not win. The first explanation seems most logical."