Sealed Move | Chess Term

Sealed move

Definition

A sealed move is a move written down but not revealed at the moment of adjournment in a long, multi-session chess game. The player to move records their next move on a scoresheet, places it in an envelope (the “seal”), and hands it to the arbiter. When the game resumes, the sealed move is opened and played on the board, and the game continues from that position.

How it works (classic adjournment procedure)

• The game reaches an agreed adjournment point (often at a time control, e.g., after 40 moves).
• The player whose turn it is writes their intended move clearly in algebraic notation (e.g., 41. Rc7, exd6 e.p., e8=Q), signs it, and seals it in an envelope along with required details (position, clocks, players).
• Both players typically sign the envelope; the arbiter keeps it in custody.
• At the next session, the arbiter opens the envelope and plays the sealed move on the board; clocks are then restarted.
• If the sealed move leads to checkmate or any decisive result, that result stands immediately upon opening.
• Ambiguities and disputes (e.g., illegible or illegal sealed moves) were handled by competition regulations of the time; arbiters applied specific procedures to interpret or rule on the move.

Why sealed moves existed

Before strong chess engines and faster time controls, top tournaments and matches often adjourned games to avoid excessively long sessions. The sealed move addressed a fairness issue: without it, the player to move would gain an overnight advantage by choosing their continuation after extensive analysis. With a sealed move, both sides could analyze the position, but only one side (the sealer) knew the exact first move, while the other had to prepare for multiple possibilities.

Strategic and psychological considerations

• Forcing lines vs. flexibility: Players often sealed forcing moves (checks, captures, threats) to reduce the opponent’s useful overnight preparation. Others preferred flexible moves to keep options open after the reveal.
• Workload asymmetry: The sealer knows the exact continuation and can focus analysis; the opponent must prepare for several plausible candidates (e.g., 41. Rc7, 41. Re7, or 41. Qd3), which is mentally and practically taxing.
• Deception: Body language and “fake candidates” sometimes aimed to mislead opponents about what was sealed.
• Technical precision: Clear notation matters. For promotions (e.g., e8=Q), castling (O-O or O-O-O), and en-passant captures (exd6 e.p.), precision avoids disputes.

Historical significance

Sealed moves were a staple of elite chess in the mid-20th century through the 1980s, including World Championship matches (Botvinnik’s era through Fischer vs. Spassky, 1972, and Karpov–Kasparov in the 1980s). Teams of “seconds” analyzed adjourned positions overnight, and newspapers often speculated about the mysterious sealed move. As engines became powerful and event formats accelerated (with increments replacing adjournments), sealed moves became obsolete in most over-the-board events. Modern FIDE events no longer adjourn games, so sealed moves are now largely of historical interest, appearing only in rare special formats or exhibitions.

Example scenario

Imagine a classical game reaches the time control with the position after 40...Kh7 and White to move. White seals 41. Rc7, intending to invade on the 7th rank. Overnight, White’s team analyzes continuations after 41. Rc7, while Black must consider several candidates (41. Rc7, 41. Re7, 41. Qd3, etc.). At resumption, the arbiter opens the envelope, plays 41. Rc7 on the board, and the game proceeds, for example: 41...Qd6 42. Qxf7 Qxc7 43. Qxc7, heading into a favorable endgame for White. The key point is the preparation imbalance: only the sealer knew for sure that 41. Rc7 was coming.

Famous contexts and stories

• World Championship adjournments: Matches such as Fischer–Spassky (1972) and the Karpov–Kasparov series (1984–1985) featured many adjourned games. Overnight analysis around sealed moves became a central part of match strategy.
• Media drama: The opening of the sealed envelope at the board was a small ritual that generated suspense for players, commentators, and spectators.
• Team preparation: In adjournment eras, top players relied on teams to analyze dozens of variations from potential sealed-move positions, a practice largely replaced today by real-time engine checking during preparation for future rounds (not during play).

Practical tips (if you ever face one)

• Write the move legibly and unambiguously in algebraic notation.
• Specify promotions (e8=Q), castling (O-O/O-O-O), and en passant (e.g., exd6 e.p.) explicitly.
• Consider sealing a move that either forces the play into your preparation or maximizes your opponent’s prep burden.
• Double-check that the move is legal in the current position before sealing.

Interesting facts

• In some events, the envelope also contained a diagram or full scoresheet to avoid later reconstruction errors.
• Adjournments gave rise to a distinctive endgame culture: entire teams spent hours analyzing adjourned rook or minor-piece endings overnight.
• The decline of sealed moves mirrors the shift in chess formats toward faster time controls and anti-cheating measures that keep all analysis strictly away from ongoing games.