According to theatrical legend–which, because it’s legend cannot be validated–The Merry Wives of Windsor exists because Shakespeare had been told by his patron, Queen Elizabeth, that she wanted to see “Falstaff in love.”
It’s a great story. The only problem is that the first time we hear this legend, it’s a hundred years later and the legend is brought forth by English dramatist John Dennis.
Let’s say it’s true, though… what are our clues?
The repeated references to the Order of the Garter (and the Garter Inn) would seem to point a performance around April 23, 1597, when Elizabeth attended the Garter Feast. This “Garter Theory” ties the arrival of the German duke (referenced in Act Four) to the contemporary arrival of Frederick I, Duke of Württemberg, who became a member of the Order of the Garter in 1597.
This would put The Merry Wives between The First and Second Parts of Henry the Fourth.
This makes sense to me: The lovable Falstaff of The First Part would most certainly create the desire to see his further adventures (especially in a decidedly NON-historical setting); the not-so-lovable version from The Second Part… well, I’d be hard-pressed to want to see THAT guy in love.