HistoryData
Historical ConflictSalamanca

Siege of the Salamanca forts

The fall of the Salamanca forts opened Wellington's advance and gave Marmont a false impression of Allied passivity that led to his defeat at Salamanca.

Duration & Scope

1812 ongoing

< 1 year

Key Facts

Dates
17–27 June 1812
French garrison strength
800 men
Allied besieging army
48,000 men
French relief force
40,000 men under Marmont
Duration
10 days

Strategic Narrative Overview

Wellington's 48,000-strong force invested the three fortified convents on 17 June 1812, but insufficient artillery ammunition slowed proceedings. Marmont marched a 40,000-man relief army but could not break the Allied cordon. A premature British storm on 23 June was repulsed by the 800-man garrison under Lieutenant Colonel Duchemin. Sustained artillery fire eventually breached one fort and set another ablaze, compelling the garrison to surrender on 27 June after ten days of resistance.

01 / The Origins

During the Peninsular War, Wellington's Allied army advanced into Spain in mid-1812 seeking to exploit French strategic overextension. Salamanca held three convents converted into fortified strongpoints by the French, blocking a clean Allied occupation of the city. Reducing these forts was a prerequisite for Wellington's broader offensive campaign against Marshal Marmont's Army of Portugal, making the siege a necessary preliminary operation before any major maneuver could proceed.

03 / The Outcome

The French garrison surrendered on 27 June 1812, clearing Salamanca for Allied use. Marmont's failed relief attempt left him with the mistaken belief that Wellington would only act defensively. This misjudgment proved fatal a month later: Marmont overextended his army and was decisively defeated at the Battle of Salamanca on 22 July 1812, a victory that opened the road to Madrid for Wellington.

Belligerents & Mobilization Analysis

Side A

1 belligerent

Allied Army (Britain, Portugal, Spain)
Peak Mobilized Forces~48K
Forces vs Casualties ratio
0Mobilized
Key Commanders

Arthur Wellesley, Lord Wellington.

Side B

1 belligerent

French Imperial garrison
Peak Mobilized Forces800
Forces vs Casualties ratio
0Mobilized
Key Commanders

Lieutenant Colonel Duchemin, Marshal Auguste de Marmont.

Outcome
Allied victory; French garrison surrendered 27 June 1812 after artillery breach; Marmont's relief attempt failed

Kinetic Engagement Axis

Major engagements timeline (1812–present)Timeline of major military engagements plotted chronologically.1812present1812Storm of the Sal…Allied1812Surrender of the…Side B

Scroll horizontally to view full axis. Events plotted relatively.

Side A victorySide B victoryInconclusiveDecisive / turning point

Location

Map of Salamanca, SpainMap of Salamanca, SpainSalamanca, Spain