Isaac Efimovich Boleslavsky (also spelled Boleslavski) was a Soviet chess Grandmaster. He was born on June 9, 1919, in Zolotonosha, Ukraine, and died on February 15, 1977 in Minsk, Belarus. An important player in the mid-20th century, Boleslavsky was also noted as a successful author and analyzer.
Boleslavsky had some significant accomplishments in his competitive career. In 1945 he captained the Soviet team to victory in the famous USSR-USA radio match. He twice reached the final Candidates match stage, coming tantalisingly close to a World Championship match both times before eventually falling short.
He qualified from the 1950 Candidates Tournament, without losing a single game, and finishing equal first with David Bronstein. Boleslavsky was well aware of the strengths of all the candidates. He was particularly good in defence, though he also showed very dynamic play and great skill in maintaining the initiative.
In addition to his playing record, he contributed important work to the 'King's Indian' defence and 'Sicilian' defence chess tactics. His greatest contribution is considered to be his opening preparation and analysis.
Boleslavsky had a quiet and placid personality, a characteristic which made him popular among his contemporaries. He liked to utilize detailed analysis of opponents as far back as 15 years and use the information to his advantage. He was also a chess teacher and coach. His style was characterised by careful planning, strong positional understanding, and a preference for the endgame.
After his retirement, he became the head trainer of the Soviet chess team, guiding the team to numerous victories. He also wrote several respected books about chess, contributing significantly to chess literature. His daughters, Tatiana and Olga, became Woman International Masters.