The following is based on Caxton's The Game and Playe of Chesse from the 1470s, a translation of the late 13th c. Liber de moribus hominum et officiis nobilium super ludo scacchorum of Jacobus de Cessolis, probably primarily a translation of a French translation of the original. The book uses chess as the starting point for an elaborate allegory about medieval society.
So, I edited out most of the allegory to get to the chess rules. But the work also uses the allegory as positional notation: each of the eight pawns on each side represents a specific type of commoner. So I needed to add some explanation of the movement rules in italics that doesn't depend on the allegory.
This is a slower game than modern chess. Queens and bishops (alphyns or judges in Caxton) are much slower and weaker than in the modern game. Their powering up for the modern game started around this time in Iberia, Italy and France, but took time to spread .
The Game and Playe of Chesse
And in this playe we ought to knowe by the nature of hit how the kynge meueth hym and yssueth oute of his place/ For y'e shall vnderstande that he is sette in the fourth quadrante or poynt of theschequer. And whan he is black/ he standeth in the white/ and the knyght on his ryght side in white/ And the Alphyn and the rooke in black/ And on the lifte side the foure holden the places opposite/
For whan he wele meue hym/ he ought not to passe at the first draught the nombre of .iii. poynts/ And whan he begynneth thus to meue from his whyt point/ He may move ii ponts either right or cornerly/ And hit happen that the aduersarie be not couered in ony poynt in the seconde ligne/ All these yssues hath y'e kyng out of his propre place of his owen vertue whan he begynneth to meue. But whan he is ones meuyd fro his propre place/ He may not meue but in to one space or poynt/ and so from one to an other/After that the kynge begynneth to meue he may lede wyth hym the quene/ after the maner of his yffue
Whan the Quene whiche is accompanyed vnto the kynge begynneth to meue from her propre place/ She goth in dowble manere/ that is to wete as an Alphyn on her first draught she may jump two points cornerwise. And whan she is meuyd ones oute of her place she may not goo but fro oon poynt to an other and yet cornerly whether hit be foreward or backward takynge or to be taken/
The manere and nature of the draught of the Alphyn is suche/ that he that is black in his propre fiege is sette on the right side of the kynge/ And he that is whyt is sette on the lifte side/ And ben callyd and named black and white/ But for no cause that they be so in subftance of her propre colour/ But for the colour of the places in whiche they ben sette/ And alleway be they black or white/ whan they ben sette in theyr places/ the alphyn goynge oute of his place comyth two spaces cornerly.
After the yssue of the Alphyns we shall deuyse to yow the yssue & the moeuynge of the knyghtes/ And we saye that the knyght on the right syde is whyt/ And on the lifte syde black/ And the yssue and moeuynge of hem bothe is in one maner whan so is that the knyght on the ryght syde Is whyt/ The lyfte knyght is black/ The moeuynge of hem is suche/that they may jump three poynts, one ryght forth going and the last at an angle.
The moeuynge and yssue of the rooks whiche ben vicairs of the kynge is suche/ that the ryght rook is black and the lifte rook is whyte/ And whan the chesse ben sette as well the nobles as the comyn peple first in their propre places/ The rooks by their propre vertue haue no wey to yssue but yf hyt be made to them by the nobles or comyn peple/ For they ben enclosed in their propre sieges/ And as fer may they renne as they fynde the tablier voyde whether hit be of his aduersaryes as of his owen felowship/ And whan the rook is in the myddell of the tablier/ he may goo whiche way he wyll in to foure right lignes on euery side/ and hit is to wete that he may in no wyse goo cornerwyse/ but allway ryght forth goynge.
One yffue and one mouynge apperteyneth vnto alle the peple/ For they may goo fro the poynt they stande in at the first meuynge vnto the thirde poynt right forth to fore them/ & whan they haue so don they may afterward meue no more but fro one poynt ryght forth in to an other/ And they may neuer retorne backward And thus goynge forth fro poynt to poynt They may gete by vertue and strengthe/ that thynge that the other noble fynde by dignyte/ And yf the knyghtes and other nobles helpe hem that they come to the ferthest lygne to fore them where theyr aduersaryes were sette. They acquyre the dignyte that the quene hath graunted to her by grace/ And y'e shall vnderftande/ whan thyse comyn peple meue right forth in her ligne/ and fynde ony noble persone or of the peple of their aduersaries sette in the poynt at on ony side to fore hym/ In that corner poynt he may take his aduersarye wherther hit be on the right side or on the lifte.
Jacobus, de Cessolis, William Caxton, and William E. A. Axon. 1883. Caxton's Game and playe of the chesse, 1474. London: E. Stock.