Lady Fights at Atherton

A poem, published in 1643, in honour of the King's successes in the West, has the following reference to a circumstance connected with Fairfax's retreat at Atherton Moor: "When none but lady staid to fight." I should be glad to learn to what this refers, and whether or not the real story formed the basis of De Foe's account of the fighting lady at Thame, laid about the same period, viz. the early part of the year 1643.