How does a cannon behave differently in the middlegame?
These answers restate the rules implemented by our open-source engine, which follows the WXF laws and is regression-tested against the official 110-diagram repetition casebook. Where an answer refers to a specific position, that position lives on the linked reference page, where the build verifies it against the engine before publishing.
Direct answer
The middlegame is the cannon's best phase. The board is still full enough to supply screens on demand, yet open enough that the cannon can actually reach targets across the board rather than being boxed in by its own side's pieces the way it can feel at the very start.
Why this window is so favourable
Early on, a cannon's own side is still crowded and its lines are shorter than they will be later. Late on, as material trades off, screens become scarce and the piece loses value as the board empties. The middlegame sits between those two limits, with maximum available screens and maximum reach at the same time.
What to do with that window
This is the phase to create concrete threats with a cannon rather than hold it in reserve. A cannon that has not done anything by the time trades start thinning the board is a cannon that missed its best moment.
Related questions
Should I trade cannons in the middlegame?
Generally not, unless it clearly favours your plan; this is when a cannon is doing the most work.
Does the middlegame favour cannons over horses?
Roughly evenly, though a cannon's threats tend to be more visible and forcing at this stage, while a horse's value keeps climbing toward the endgame.
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