Wurzburg-Plachutta: like-piece interference in chess
Wurzburg-Plachutta
Definition
The Wurzburg-Plachutta (often written Würzburg–Plachutta) is a classic interference theme in chess composition. It occurs when two like-moving line pieces (typically two bishops, or two rooks/queen as rook-movers, or two bishops/queen as bishop-movers) defend critical lines that intersect at a single square. White plays a sacrificial move to that intersection square; whichever of the two like-moving defenders captures on that square interferes with the other, closing its line. The resulting self-interference creates a decisive threat or mate. In problem jargon this is a form of interference sacrifice and a close cousin of the Plachutta.
In short: White blocks or tempts a capture on the critical intersection; Black’s capture by either of two like-moving pieces cuts the line of its partner, enabling White’s intended finish.
How it is used in chess
The Wurzburg-Plachutta is predominantly a theme of composed problems—especially directmates in two or three moves—where precise line geometry is the point of the work. It:
- Highlights pure line interference: a capture onto the intersection square disables the other like-moving defender.
- Often yields elegantly paired variations: “If the e7-bishop captures, this mate follows; if the c7-bishop captures, another mate follows.”
- Appears as a themed key move or as a dramatic sacrificial try that Black can refute only by creating the desired interference.
In practical over-the-board play, a full Wurzburg-Plachutta is rare but the underlying idea—inducing one defender to block another’s line—does appear as a tactical motif akin to Interference, Line, and Deflection.
Strategic and historical significance
The name acknowledges two pioneers: Anton Würzburg and Josef Plachutta. Historically, examples of like-piece interference appeared in Würzburg’s work; Plachutta’s later, widely circulated settings popularized the device, hence the double eponym “Würzburg–Plachutta.” The theme sits alongside its well-known relatives:
- Plachutta: Like-piece interference on a critical intersection (identical core mechanism; the terms are often used interchangeably).
- Novotny: The intersection involves unlike line pieces (usually a rook/queen-line with a bishop-line) and a white sacrificial move onto that point. Novotny is to rook+bishop as Plachutta/Wurzburg-Plachutta is to like movers.
- Grimshaw: Mutual interference between a rook and a bishop by occupying the same square; often arises as the result of a Novotny capture.
The theme is prized for its purity and logic. Composers aim to present clean dual-avoidance (distinct mating continuations after each black capture) and model mates. It frequently appears in award-winning two-movers and in tasks that combine multiple interferences or echo-variations.
Schematic example (conceptual)
Imagine Black has two bishops on c7 and e7 whose diagonals meet on d6, and those lines defend key mating squares. White plays the sacrifice 1. Nd6!!, placing a unit on the intersection d6:
- If 1... Bexd6 (the e7-bishop captures on d6), its own move blocks the c7-bishop’s diagonal. A mating line such as 2. Qc6# becomes possible because the c7-bishop’s guard has been interfered with.
- If 1... Bcxd6 (the c7-bishop captures on d6), it now interferes with the e7-bishop’s diagonal, allowing a different mate, for example 2. Qe8#.
The exact mates depend on a full composition, but the geometry is the essence: the capture by either like-moving defender shuts the other’s line, producing two clean, non-dual mates.
Mini visualization
This lightweight board marks the intersection square and the interfering lines of two bishops. The single “key move” illustrates White’s sacrificial idea onto the crossroads. Note: this is illustrative of the geometry, not a complete problem.
OTB analogue
While a textbook Wurzburg-Plachutta is uncommon in games, the logic can inform practical tactics:
- Plant a piece on a square where two like-moving defenders’ lines intersect; if either recaptures, it may block the other defender, allowing a decisive entry (e.g., a back-rank or dark-square mate).
- Seek sacrificial “decoys” that force a defender onto an awkward square, causing self-block or line-closure—akin to a practical Interference or Interference.
Related motifs and comparisons
- Plachutta: Same fundamental like-piece interference; many writers treat Wurzburg-Plachutta as synonymous with Plachutta.
- Novotny: Unlike-piece version (rook/queen-line with bishop-line).
- Grimshaw: Mutual rook–bishop interference after a capture on the common square.
- Interference, Line, Line, Deflection, Decoy: General purpose tactical relatives.
- Advanced patterns: Bristol, Turton, Critical—all involve line geometry and clearance ideas that sometimes combine with Wurzburg-Plachutta settings.
Examples you can look for in problems
- Two bishops on c7 and e7; intersection d6; key 1. Nd6!!. If ...Bexd6 then White mates on the c-file; if ...Bcxd6 then White mates on the e-file. The mates are paired and non-dual.
- Two rooks guarding along a file and rank where the intersection is c7; key 1. Rc7!!. If ...Rxc7, one rook’s capture blocks the other’s line; if ...R7xc7 instead, a different mate results. This is a rook-mover Wurzburg-Plachutta.
Composers often craft mirror-image or echo mates after the two recaptures to emphasize thematic clarity.
Interesting facts and anecdotes
- Spelling: You’ll see Würzburg–Plachutta (with umlaut) and Wurzburg-Plachutta (ASCII). Both refer to the same interference theme.
- Credit: The dual name honors Anton Würzburg’s early like-piece interference ideas and Josef Plachutta’s influential, widely cited settings.
- Theme families: Many award-winning two-move tasks combine a Wurzburg-Plachutta with a Novotny or finish in a Grimshaw after the first capture.
Tips for solvers and analysts
- Identify two like-moving defenders whose lines cross a key square.
- Search for a sacrificial key that forces a capture onto that square.
- Verify dual avoidance: after each capture, your intended mate or threat should rely specifically on the line that has been blocked.
- In OTB, translate the idea into practical terms: lure a defender to a blocking square to switch off its partner.