She rose as high as His Occasion — Queen Elizabeth I

She rose as high as His Occasion
Then sought the Dust-
And lower lay in low Westminster
For Her brief Crest-
(F.1019/J.1011)
[1] His Occasion:: God's occasion, a hint on Virgin Queen and Virgin Mary.
[2] sought the Dust:: to rule the disordered England, an earthly task from God's view.
[3] Westminster:: the Queen was buried in Westminster Abbey.
[4] brief Crest:: the brief title of Virgin Queen, to match as high as "His" occasion.

For Dickinson, the "His" was her father's, and she sought the earthly life under her father's request. After death, her poems might appear in lower corner of some magazines, e.g. Westminster Review, a brief crest of her writing life.