Giulio Cesare Polerio (ca. 1550, Lanciano - ca. 1610, Rome, reconstruction of places and dates by Adriano Chicco), was an Italian chess theoretician and player.
Name affixes used for him are l'Apruzzese, Giu[o]lio Cesare da Lanciano (Salvio/Walker), and Lancianese, because he was born in Lanciano, a town in the Chieti province of the Abruzzo region of Italy.
The first printed matter, in which the name Giulio Cesare da Lanciano occurs, is the so-called "Il Puttino" of Alessandro Salvio published first in 1634. The story recounted in Il Puttino must have occurred around 1575, thus, published by Salvio some 60 years later. "Il Puttino, altramente detto il Cavaliere errante" is a nickname used by Alessandro Salvio for Giovanni Leonardo. According to Alessandro Salvio, Giulio Cesare da Lanciano accompanied Giovanni Leonardo on his way to Madrid until Genoa.
After returning to Rome around 1584, Polerio became a chess player and writer in ordinary of Giacomo Boncompagni, Duke of Sora and son of Pope Gregory XIII (born Ugo Boncompagni).
Polerio wrote a number of codexes in which a lively international chess is described (exchanges of ideas among Italy, Portugal, and Spain). In these codexes, besides of own and new ideas in chess openings, some matches played by himself are noted by the hand of Polerio.
In the Puttino, Salvio mentions that, starting in 1606 from "Città di Piazza", after a long travel on his way to Rome (p. 43) ... (p. 44: "il detto Signor Cascio poi andando a Roma, vinse Giulio Cesare compagno del Puttino il primo a Roma, in casa dell'Eccelenza del Sig. Giacobo Buoncompagno Duca di Sora") this Mr. Geronimo Cascio, on his way to Rome, beat Giulio Cesare (Polerio), companion of Il Puttino, the best in Rome, in the house/court of his Excellence Giacomo Boncompagni, Duke of Sora.
The first systematic investigation of the Codexes of Polerio was published by Antonius van der Linde in 1874. The subject of the investigations by Van der Linde can be found at the Bibliotheca Van der Linde-Niemeijeriana, part of the Koninklijke Bibliotheek, National Library of the Netherlands.
The current systematics of the Codexes of Polerio has been performed and published by Alessandro Sanvito in 2005.
The systematic organisation of overall seven Codexes, described and called A-G by Van der Linde, and attributed to Polerio in 1874, had major impact on the further description of chess history, and history of chess theory. A relevant part of the work of Van der Linde was to compare Codexes of Polerio and Gioacchino Greco even superfine. According to this investigation, most of the analytic work of Polerio was mediated outside of Italy, up to 1874, via Gioacchino Greco. The clue, which potentially could link both chess players, may be seen in the person Giacomo Boncompagni, or the Duchy of Sora respectively.
On p. 186 of "Das Schachspiel des XVI. Jahrhunderts" van der Linde wrote in 1874:
1. e2-e4 e7-e5 2. f2-f4 e5-f4: 3. Sg1-f3 g7-g5 4. Lf1-c4 g5-g4 5. 0-0! g4-f3: 6. Dd1-f3: e cosi ancor che habbia perso un pezzo resta con buonissima postura di poter uencere il gioco sapendo guidarlo à presso, il che sarebbe superfluo inogni modo se si uolesse mostrare la fine di tutti giochi, e per questo basta insino à un certo che, tanto che si conosca apartemente il uantagio del gioco, si come per la postura di dette giochi ogni giudicioso giocatore lo potrà facilmente cognoscere.")
... in modern terms:
"Polerio Gambit: 1. e4 e5 2.f4 exf4 3. Nf3 g5 4.Bc4 g4 5.0-0! gxf3 6.Qxf3 +/-"
Exactly this move order was also found later even in a second Polerio Codex discovered and described by J.A. Leon in 1894. Of note is that the position after 1. e4 e5 2.f4 exf4 3. Nf3 g5 4.Bc4 g4 5.0-0 gxf3 6.Qxf3 may be considered by most recent grandmasters as a forced win for White - provided that 5.0-0 would mean "free castling", i.e. bringing the White King from e1 to h1. Actually, Polerio did claim 5.0-0 gxf3 6.Qxf3 to be favourable for White although the White King of Polerio did stand, after 5.0-0, on h1 but not on g1 (i.e. castling as defined in our days).
However, in 1874, the move order 1. e4 e5 2.f4 exf4 3. Nf3 g5 4.Bc4 g4 5.0-0! was already occupied by the term "Muzio Gambit". This term derives from a translation of a work of Alessandro Salvio, supposedly the third book of the reprint of 1723, by Sarrat in 1813. On page 209 Jacob Henry Sarratt (translated) and wrote:
"SALVIO states that the following Gambit was sent to him by Signor Muzio, ..."
Actually, Alessandro Salvio never stated this. Rather, in the third book of the Il Puttino he wrote that Signor Mut io d'Alessandro did see that Geronimo Cascio did play the move order (with free castling, also called "Italian method" of castling).
With p. 165, vol. 2, of the 1821 edition of A New Treatise of the Game of Chess the term Muzio Gambit was coined by Jacob Henry Sarratt. And with the latter work of Sarrat, in 1821 the modern theory of the "Muzio Gambit" with castling according modern rules started - an idea and a position already Polerio analysed in 1579/80.
Thus, Antonius van der Linde, changed the view on the historical development of the move order 1.e4 e5 2.f4 exf4 3.Nf3 g5 4.Bc4 g4 5.0-0 in 1874, most notably in the last editions of the Handbuch. Thereafter, a trend can be seen to call this move order either with hypenated terms such as Muzio-Polerio, Polerio-Muzio, or simply Polerio Gambit. Such a terminology is both in honour of Giulio Cesare Polerio and partially misleading since the major body of the theory of this opening was generated in the time span in-between 1821 and 1874. The number of games played by Adolf Anderssen, Paul Morphy, and Wilhelm Steinitz with 1.e4 e5 2.f4 exf4 3.Nf3 g5 4.Bc4 g4 5.0-0 or 5.d4 in the time span 1821-1874 was already rather high. The rules for Chess opening nomenclature, and their historical development, should be taken into account while assessing van der Linde's claim of 1874 "D. Polerio-Gambit".
In 1874, Van der Linde suggested as well (p. 188) to rename the move order 1. e4 e5 2. f4 ef 3.Nf3 g5 4.Bc4 Bg7 5.h4 h6 6.d4 d6 7.Nc3 e6 8.hg hg 9.Rxh8 Bxh8 10.Ne5 into "Polerio's second Gambit". This suggestion is based on the observation that "im Handbuch (1864, S.. 366, § 3)" this move order is called "das Gambit des Calabresen". This is a rather interesting observation since in the "Handbuch" in its 2nd edition as of 1852, on p. 205 it is mentioned that the move order 1.e4 e5 2.Bc4 f5 can be found "at the Calabrese". That's a rather wise wording since both 1.e4 e5 2.Bc4 f5 and 1.e4 e5 2.Nf3 f5, according to Codexes of Polerio, occurred in games of "Gio. Leonardo" (games 236-238, p. 190 in van der Linde). Both Giovanni Leonardo and Gioacchino Greco derived from Calabria, the first from Cutro, the second from Celico(?).