War of the Two Peters(1369)
1356 - 1369
Kingdom of Castile and Allies
Commander: Peter I (Peter the Cruel)
Initial Combat Strength
%43
ⓘ Analysis Parameter: Raw combat force projection only. Does not reflect the mathematical average of operational quality scores.
Decisive Force Multiplier: English mercenaries and the elite troops of Edward, the Black Prince, provided the Castilian army with the most modern tactics and experience in Europe.
Crown of Aragon and Allies
Commander: Peter IV (Peter the Ceremonious)
Initial Combat Strength
%57
ⓘ Analysis Parameter: Raw combat force projection only. Does not reflect the mathematical average of operational quality scores.
Decisive Force Multiplier: French support and capable commanders like Bertrand du Guesclin allowed successful hit-and-run tactics.
Final Force Projection
Post-battle strength after attrition and strategic wear
Operational Capacity Matrix
5 Military Metrics — Staff Scoring System
While Castile had larger manpower and grain resources, Aragon financed the war through coastal trade and French financial aid. The Black Death and famine struck both sides, but Castile's internal revolts made its logistics more fragile. Although Aragon's economy collapsed at the end, it secured minimum resources from allies to prolong the war.
Aragon King Peter IV managed the war through diplomatic maneuvers, using capable envoys and commanders like Bernardo de Cabrera. In Castile, Peter I's centralized and cruel rule triggered internal opposition, weakening the chain of command. Aragon's coalition governance allowed more flexible decision-making.
Aragon exploited its defensive advantage, countering Castilian deep advances with guerrilla tactics. The rugged terrain and castles of Valencia particularly slowed the Castilian operational tempo. The Castilian army often moved with plunder-focused operations, missing strategic objectives.
Aragon's intelligence network with France and contacts with Castilian opposition determined the war's direction. Castile relied on intelligence from English allies but suffered from intelligence vulnerability due to internal revolts. Henry of Trastámara's defection granted Aragon critical information superiority.
English longbowmen and heavy cavalry tactics gave Castile an initial edge. Aragon responded with French mercenaries and Bertrand du Guesclin's flexible infantry tactics. Morally, Castile lacked popular support, while Aragon's 'national defense' motif motivated its troops.
Strategic Gains & Victory Analysis
Long-term strategic gains assessment after battle
Victor's Strategic Gains
- ›The Anglo-Castilian naval alliance weakened, while Aragon strengthened its strategic position in the Mediterranean.
- ›Aragon secured Castile's southern borders, enabling continued expansion policy.
Defeated Party's Losses
- ›The Castilian throne changed hands, and the legitimate dynasty lost power, deeply shaken by civil war.
- ›The protracted war heavily devastated the Castilian economy and population, tilting the regional balance in favor of Aragon.
Tactical Inventory & War Weapons
Critical weapons systems and combat vehicles engaged in battle
Kingdom of Castile and Allies
- English Longbow
- Heavy Armored Knight
- Castilian Galley
- Siege Mangonel
- Genoese Crossbow
Crown of Aragon and Allies
- French Mercenary Infantry
- Ballista and Artillery
- Aragonese Galley
- Mountain Light Cavalry
- Defensive Towers
Losses & Casualty Report
Confirmed and estimated casualties sustained by both parties as a result of battle
Kingdom of Castile and Allies
- 8000+ PersonnelEstimated
- 22+ CastlesConfirmed
- 40+ ShipsIntelligence Report
- 1x Legitimate RulerConfirmed
- 2x Allied SupportUnverified
Crown of Aragon and Allies
- 6500+ PersonnelEstimated
- 15+ CastlesConfirmed
- 30+ ShipsIntelligence Report
- Economic CollapseConfirmed
- 3x Territorial ContractsUnverified
Asian Art of War
Victory Without Fighting · Intelligence Asymmetry · Heaven and Earth
Victory Without Fighting
Aragon King Peter IV fanned the legitimacy crisis in Castile before the war and made secret agreements with Henry of Trastámara. He successfully applied the strategy of wearing down the enemy without fighting by dragging Castile into a civil war through diplomacy. Although Castile attracted Portugal and Navarre as allies, it could not sustain these alliances.
Intelligence Asymmetry
Through its spy network in the Castilian court, Aragon learned of Peter I's plans in advance and timely reinforced critical points like Tarazona and Calatayud. Castile failed to fully assess Aragon's French connection and could not prevent Bertrand du Guesclin's arrival in Iberia. Henry of Trastámara's refugee status provided Aragon with a unique intelligence source.
Heaven and Earth
Summer droughts and locust invasions strained both armies' supply lines, prolonging the war. Aragon's mountainous interior and Valencia's wetlands limited the effectiveness of Castile's heavy cavalry. Winter truces showed that seasonal conditions dictated the war's rhythm.
Western War Doctrines
Attrition War
Maneuver & Interior Lines
Aragon used its interior lines advantage to swiftly shift troops to threatened areas. Particularly on the Segorbe-Morvedre line, it halted the Castilian advance with rapid maneuvers. Castile advanced slowly on multiple fronts and struggled to hold captured castles. Reinforcement by French mercenaries enhanced Aragon's maneuverability.
Psychological Warfare & Morale
In Castile, Peter I's reputation as 'the Cruel' and his violence against the nobility caused morale collapse among the populace and army. In Aragon, Peter IV's diplomatic successes, symbolized by his 'the Ceremonious' epithet, raised the fighting spirit of troops. Explainable with Clausewitz's concept of 'friction,' internal strife paralyzed the Castilian war machine.
Firepower & Shock Effect
Castile shook the Aragonese infantry with long-range firepower from English longbows, but lacked the opportunity to follow up with cavalry charges. Aragon was more effective in artillery use, achieving fire superiority in castle defense. Bertrand du Guesclin's mercenaries caused panic in Castilian lines with sudden raids.
Adaptive Staff Rationalism
Center of Gravity · Intelligence · Dynamism
Center of Gravity
The Aragonese High Command focused its center of gravity on defending the Valencia region, wearing down Castile's main offensive power there. Castile failed to clearly define its center of gravity, unnecessarily massing forces against fortified positions like Calatayud. Aragon correctly identified the Castilian throne as the true center of gravity, sparking the civil war.
Deception & Intelligence
Aragon employed a strategy of collapsing Castile from within by supporting Henry of Trastámara. Peter IV's secret agreements with France and his readiness to deploy Bertrand du Guesclin's mercenaries were the greatest deception that won the war. Castile remained passive in diplomatic deception and failed to break Aragon's alliances with Navarre and Portugal.
Asymmetric Flexibility
Aragon demonstrated asymmetric flexibility by applying mobile defense and hit-and-run tactics rather than static trench warfare. Castile could not adapt its heavy-cavalry-oriented doctrine to changing conditions and failed to move beyond plundering expeditions. Aragon's use of mercenaries provided doctrinal diversity.
Section I
Staff Analysis
The War of the Two Peters was a war of attrition waged by feudal forces for dynastic interests. Initially, Castile seemed superior with English military technology and larger manpower, but Peter I's cruel rule fueled internal opposition and undermined strategic continuity. Aragon, under Peter IV's diplomatic skill and French military support, maintained defensive superiority and turned the conflict into a Castilian civil war, thereby winning. Examining military metrics, Aragon shows clear advantages in C2 and time-space utilization. Although Castile had logistical advantages, it failed to leverage them. The result is an Aragonese strategic victory despite Castilian tactical successes.
Section II
Strategic Critique
The Castilian High Command identified the main strategic objective (full annexation of Valencia) but lacked the operational planning to achieve it. Unnecessary force concentration like the siege of Calatayud, raids turning into plunder, and failure to suppress internal opposition were critical errors. The Aragonese High Command, however, relied more on political maneuvering than military force to win; a correct decision, but it ignored economic resilience. The post-war economic collapse was a result of short-sightedness. The decisive moment was Peter IV's deepening alliance with France in 1363, bringing capable commanders like Bertrand du Guesclin to the field. This forced Castile into a two-front war and prepared its final collapse.
Other reports you may want to explore