I know it's supposedly a "myth" that the rapier was a light, flimsy weapon only useful in duels and civilian contexts. But while there's probably a fair amount of truth to that, it seems that quite a lot of primary sources during 1500-1700 really do express disdain for the rapier as a military weapon.

George Silver is probably the best known critic, but even he mentions that at the time rapiers were rarely used in actual warfare. (He just didn't like the military short sword either since it didn't have a hilt):

Quote:

To this it will be objected, that in the wars we use few rapiers, or none at all, but short swords. To that I answer: Those are insufficient also, for that they have no hilts, whereby they are insufficient in their defence, and especially for the hand, which being struck although with a very small blow, most commonly is the loss of a man, because the force of his hand being taken from him, he is neither able to defend his life, nor greatly to offend his enemy. And again, since the rapier-fight has been taught, for lack of practice they have lost the use of the blow.

I've also been finding that a lot of the military swords translated as "rapiers", for example the "rapier" used by Swedish soldiers under Gustavus Adolphus, were still only about a meter long overall (even shorter than Silver's ideal short sword) and intended to both cut well and thrust well.

William Garrard, who had formerly fought in the Spanish army and was writing in the 1580s, is an example of a writer who tended to switch back and fourth between "sword" and "rapier" interchangeably but still stressed that military sidearms shouldn't be too long:

Quote:

Both the Hargabusier and Pykeman must weare a short Rapier and a small Poinado: For if in the middest of Encounters and Skirmishes, they be driuen to vse them, their length is an occasion they cannot be drawen, vnlesse hee a∣bandon his Peece or Pike, whereby hee shall either loose his Pike, or want his Rapier, which at the Sera and Close is verie necessarie both for Defence and Offence

Quote:

Whilest a Souldier is in the Campe, hee ought neuer to lye out of his clothes, his Peece ready charged must lye by his side, his furniture at his girdle, which is his Flaske, Match & Tutchboxe, his Rapier very ready, and his Poynado likewise at his Girdle, which if they should be so monstrous Daggers, or such a Cutlers shop as our English Fēsers [Fencers] are accustomed to wear, they would be both combrous in cariage, and troublesome to his companions, and to himselfe, specially when they lye in their Cabbines.

From Sir James Turner, writing in 1671:

Quote:

The Scots and English used constantly broad Swords, for if we believe some of the English Histories, a Rapier is so new a Weapon in England, that it is not yet above one hundred years old. In the time of the late Troubles in England long Rapiers were used for a while, and then laid aside.

He later does suggest that the long rapier along with other 'medieval' weapons might still be useful in siege warfare if there are any available:

Quote:

[Other Weapons for Foot.] There are besides these I have mention'd, other Weapons for the Foot, such as long Rapiers and Touks, Shables, two handed Swords, Hangmens Swords, Javelins, Morning stars, but most of these are rather for the defence of Towns, Forts, Trenches, Batteries and Approaches, than for the Field. And as our light armed Foot are now for the most part armed with Sword and Musket, so our heavy arm'd offensively are with Sword and Pike.

Well the soldiers of Gustavus Adolphus were not using rapiers to begin with, the idea that they did is based on the modern day translation of the Swedish word "värja" being "rapier" and the fact hat Swedish historians have been pretty sloppy with the terminology for swords & rapiers as documented during that period.

At the time a proper rapier would have been recorded as a "rappir", while "värja" simply was "arm" as in "sidearm" or iused for weapons in general. (I.e pikes and muskets were "långa värjor" i.e "long arms".)
Depending on the document the same weapon may be recorded as "värja" in one and then as a "degen" i.e sword in the next as you trace a shipment of weapons.

If you look at the weapons themselves there are few if any traces of them being rapier style weapons, for example the "värja" used as a sidearm by the infantry during the 1670's was a short cutting sword with only limited thrusting capability.

A better translation of the word "värja" is badly needed for when the word is used in a 16th to early 18th century context but few if any translators are experts on sword types and there is no good word that matches the Swedish use in English afaik.

Henry,

The difficulty of these sources is that many seem to be "prescriptive", rather than "descriptive". In other words, they express what the authors think ought to be, which is usually in contrast with what is actually happening. Consequently, it's difficult to say to what extent long rapiers saw use on a battlefield by relying on critical sources.