"Attack him where he is unprepared, appear where you are not expected."
— Sun Tzu, The Art of War, Chapter I
Doctrine note: Vectors are how the unexpected appearance is structured. The primary vector applies pressure where the opponent expects it. The secondary vector appears where they do not. The reserve holds the options neither has yet committed. Together they create the condition Sun Tzu describes — simultaneous threats the opponent cannot address without abandoning one.
Every multi-front operation must be structured so that each vector serves a distinct purpose. Not multiple vectors pursuing the same objective from different directions — each vector creating conditions that the others exploit. The primary vector applies direct pressure. The secondary vector denies the opponent the ability to concentrate against the primary. The reserve holds options that neither the primary nor the secondary commits.
The Three Vectors
- Primary VectorThe main effort — the vector that, if successful, achieves the primary objective. Receives the majority of available resources and the most capable elements of the force. Applies direct, sustained pressure at the selected engagement point. Does not have to be the most visible vector — in well-designed operations, the primary often appears secondary until it is too late for the opponent to reposition.
- Secondary VectorThe supporting effort — whose primary purpose is to prevent the opponent from concentrating full force against the primary vector. Creates a genuine second threat the opponent cannot afford to ignore. The secondary vector either achieves its objective independently — in which case it becomes co-equal — or exists solely to enable the primary. Both outcomes are acceptable. What is not acceptable: a secondary vector that is so obviously secondary that the opponent correctly identifies it and concentrates against the primary anyway.
- Reserve VectorThe uncommitted capability. Not a failure to commit — the deliberate preservation of optionality. No operation unfolds exactly as planned. The commander who has committed all available force to the initial plan has no response to conditions that diverge from it. The reserve is the capacity to respond to what neither the primary nor the secondary anticipated. It is the most undervalued element in most multi-vector operations.
Named Concept
Vector Discipline
The most common vector error: dispersing force across too many simultaneous vectors — dividing available resources so thinly that no single vector has sufficient force to achieve its objective. This is the appearance of multi-front warfare without its substance. Each vector must have enough force to achieve its specific purpose. If the available resources cannot support three vectors at the required level — restructure to two, or one. Thin vectors everywhere produce weakness everywhere.
Case Study — Vector Structure Applied
Hannibal at Cannae, 216 BC — The Perfect Envelopment
Primary Vector — The Center
The Gallic and Spanish infantry in the center were deployed in a convex formation — bulging toward the Romans. Their purpose: absorb the Roman assault and retreat slowly, drawing the Romans forward into a deepening pocket. They were the primary vector not because they would win — they were expected to be pushed back — but because their retreat created the conditions for the secondary vectors to close.
Secondary Vectors — The Wings
African heavy infantry on the flanks — held back while the center absorbed pressure. As the Roman legions pressed forward into the center, the African wings swung inward from both sides simultaneously. The Romans could not respond — they had concentrated against the center and had no reserve capable of addressing both flanks at once. The secondary vectors became co-equal with the primary at the moment of execution.
Reserve Vector — The Cavalry
Hasdrubal's heavy cavalry on the left defeated the Roman cavalry opposite them, then rode around the entire battlefield to attack the Italian allied cavalry on the right — completing the encirclement from behind. The cavalry reserve was not committed until the center and flanks had created the conditions that made its commitment decisive. Premature cavalry commitment would have left the encirclement incomplete.
The Vector Structure as a System
Each vector depended on the others executing correctly and in sequence. The center had to hold long enough for the wings to close. The wings had to close before the Romans could turn to face them. The cavalry had to complete the encirclement before the Romans could break out. This is vector discipline: every element serving its specific purpose, in sequence, producing a result no single element could achieve alone.
The Mastermind
"The reserve is most valuable at exactly the moment when everything appears to be going well — because that is the moment when the opponent is most likely to reveal a response that neither the primary nor the secondary anticipated. Do not commit the reserve to confirm a victory that is already decided. Hold it for the development the plan did not account for."
VII
Divide the opposing force before engaging it. A unified opponent is always more dangerous than a divided one.
The vector structure is the operational mechanism for division. The primary vector fixes the opponent's attention and resources. The secondary vector forces a choice. The reserve holds the decisive response. Together they create the division that makes the opponent unable to concentrate full force at any single point.
Maxim References
⚔vii
Warfare Maxim VII
Divide the opposing force before engaging it. The vector structure is how division is operationalized.
⚔x
Warfare Maxim X
The Masterstroke is built over time — not seized in a moment. The vector structure is what prepares the conditions for the decisive action.
Vectors Across All Four Domains
- ChessPrimary vector: the main plan — the passed pawn, the king attack, the outpost. Secondary vector: a diversion that prevents the opponent from consolidating defense. Reserve: a tactical resource held back until the conditions are right.
- PoliticsPrimary vector: the main influence objective. Secondary vector: a parallel engagement that divides the opponent's political resources. Reserve: political capital held back from both vectors for the unexpected development.
- EconomicsPrimary vector: the main investment thesis. Secondary vector: a complementary investment that reinforces the primary or creates an independent return. Reserve: uncommitted capital available when opportunity arises.
Maxim References
◈vii
Mastermind Maxim VII
Every advantage has a window. The vector structure is how you build toward it.
◈x
Mastermind Maxim X
The Masterstroke is not a brilliant improvisation. The vector structure prepares the conditions for it.