The Montero cap is like marmite, some people really like them whilst others don’t. There are very few references of monteros being worn, and even fewer images that can reliably be set in England in the 1640s. Montero above by The 1642 Tailor
In Magnalia Dei Anglicana. Or Englands Parliamentary Chronicle
By John Vicars, published in 1646, this story relates how Prince Rupert was mistaken for Thomas Fairfax in the heat of battle because they were both wearing similar monteros:
“And, heer (as wee have it from credible relation) a party of the enemies brake through our left wing of Horse, came quite behinde our Rear of our Train, the Leader of them being a person somewhat in habite like our Generall, in a red Montero, as our Generall had; Hee came as a friend, and our Commander of the guard of the Train went with his hat in his hand, and asked him how the day went, thinking verily hee had been our Generall; The Cavalier (who wee since heard for certain was Rupert) asked him and the rest, if they would have quarter, whereupon, they cryed no, gave fire instantly, and most bravely beat him off, making him flie for his life, and his companions.”
And in this account by Anthony Wood from his diary for 1643 in Oxford there are details an issue of suits and montero caps:
“all the common soldiers then at Oxford were new appareled, some all in red, coats, breeches and mounteers; & some all in blewe”
It is thought that the origins of the Montero were on the continent and that it was a hunting hat, as the Oxford English Dictionary says:
“A cap of a type formerly worn in Spain for hunting, having a spherical crown and (freq. fur lined) flaps able to be drawn down to protect the ears and neck”. It would be a practical hat for hunting, the folded skirt of the cap would be practical in cold weather and the design also catches less wind than a broad-brimmed hat. It may also have been a higher status item than reenactors tend to portray, though as we have seen, there is at least one recorded instance of an issue to common soldiers.
Unfortunately no one really knows for sure what a montero actually looked like as there is no extant image that is labelled “here is a montero”, though there is a sketchy drawing in a The Academie of Armourie published by Randall Holme in 1688 (left) which gives us a few clues as it is labelled as a mountaro in the text. There are several images from the continent of 
soldiers wearing caps that could just fit the bill, with triangular panels making the crown, some with peaks but all having a band around the crown that could be folded flaps. This detail from a painting by Pieter de Snayers of Troops at the Siege of Aire Sur la Lys from 1653 shows a pikeman with an unfolded cap.
There is one engraving from England of Colonel Thomas Lunsford wearing a cap with a peak and
a low rounded front, very much the classic reenactor’s montero. Notice how thin the folded skirt is as it goes around the cap and the fact that you can see the lower edge of the crown beneath the skirt. Attaching the skirt in this way makes a big difference to the fit of the cap compared to just sewing it to the bottom of the crown. This is how I originally thought they were made, but looking at this and other images from the continent proves otherwise and I have born this out by practical experiment that a montero made this way is much more comfortable on the head.
In Farndon Church Cheshire there is a stained glass window showing a group of soldiers from the civil war. The drummer appears to wear a red peaked cap with gold trim. This could be another Montero, but what is interesting is that the pose and costume of the drummer is very similar to the French engraving shown here by Abraham Bosse. The montero shown below is based on this picture.
This design may also be a Montero, except that there is no peak. These two images, one a Hollar engraving, the Fflye from a Pack of Knaves, the other by Abraham Bosse, on the left entitled Envy, both show a peakless cap with piped seams or maybe braided decoration to the crown, which is made of more panels this time, maybe 12 or so and a folded band that comes to a point in front like the drummer’s one. The left hand image also shows the folding of the band. The detail does show also that the band is sewn together at the front, a clue a to how these caps were probably made. Both have a button on the top that covers the tricky part of the crown where the seams meet, and piping around the edges that keep the raw cut wool from too much fraying,though I’ve found that a good fulled broadcloth does’t actually need hemming
This is a photo of two of my reconstructed monteros, one folded and the other unfolded. I’ve tried to keep the gap that is seen in the engravings 
between the skirt and the edge of the crown, and extended the sides of the peak to meet the crown as seen in the Lunsford portrait. The cut edges are left raw which is a period technique and results in a more comfortable hat because a lot of layers can be dispensed with in the construction. It works as a cap, is comfy and looks like the pictures.
And now a third example, my best take on the peakless Hollar Fflye montero. Twelve panels in the crown and all seams are piped, just like the engraving. There is also a button on the top as all those seams tend to create a hole in the top where the rain could come in!
Banner image courtesy of Rusty Aldwinckle. Most of the other photos were taken by me.
The 1642 Tailor 