Laudator Temporis Acti

W.G. Hoskins, Old Devon (Newton Abbot: David & Charles, 1966; rpt. Pan Books, 1971) p. 146:

The Great Sweat of 1551

The sweating-sickness was a new type of infection which first reached England in the autumn of 1485. It has been suggested that it was probably a new and virulent form of influenza. Further outbreaks occurred in 1508, 1517, and 1528. The fifth and final outbreak came in 1551. Death was swift, and mortality was high.

The epidemic of 1551 began at Shrewsbury in the spring. By June it had reached Loughborough in Leicestershire, where the parish register records that the "swat, called New Acquaintance, alias Stoupe Knave and know thy Master" began on the 24th of the month. It was sometimes called Stop-Gallant because it was supposed to attack the rich and young, and to kill them within a few hours.

For 'Stop-Gallant' (sic), see OED s.v. † stoop-gallant, n., 1:

Something that humbles 'gallants'; originally, a name for the 'sweating sickness'; later used gen.

For the imperative-vocative formation, see OED, s.v. stoop v.1, 2a:

To 'bow' to superior power or authority; to humble oneself, yield obedience.

1555   R. Eden in tr. Peter Martyr of Angleria Decades of Newe Worlde Pref. sig. bjv   Stoope Englande stoope, and learne to knowe thy lorde and master.

"Autobiographical Narrative of Thomas Hancock, Minister of Poole," in John Gough Nichols, ed., Narratives of the Days of the Reformation, Chiefly from the Manuscripts of John Foxe the Martyrologist; with Two Contemporary Biographies of Archbishop Cranmer (London: The Camden Society, 1859), pp. 71-84 (at 82):

The first plage was a warning too England, which was the posting swet, that posted from towne to towne, throwghe England, and was named stope gallant,^a for hytt spared none, for ther were dawncyng in the cowrte at 9 a'clocke thatt were deadd or aleven a'clocke.

^a Another instance of this name being given to the sweating-sickness has been mentioned in the notes to Machyn's Diary. It is in the register of Uffculme, co. Devon, "the hote sickness, or stup-gallant." In the register of Loughborough in Leicestershire it is termed "the swat called New acquaintance, alias Stoup knave and know thy Master."

Hat tip: Eric Thomson.