Thin Red Line
Thin Red Line is a Commerce Age British Church technology that makes Musketeers tougher but slower. It increases their hit points by 20% and reduces their speed by 10%, so the upgrade favors holding power over rapid movement.

Research profile
- Civilization & Age
- British · Commerce Age
- Building & prerequisite
- Church · The Glorious Revolution Home City Card
- Research time
- 15 seconds
- Effect
- Musketeer hit points +20% · speed −10%
Research effect
The technology requires The Glorious Revolution Home City Card and takes 15 seconds to research at a Church. Its effect applies to Musketeers under the British rules; it does not improve every British unit. The speed penalty affects how quickly the line can reach a fight, pursue, retreat or respond to another front.
Research condition
British · Commerce Age · Church · requires The Glorious Revolution Home City Card · 15 seconds · Musketeer hit points +20% · speed −10%.
Cost and prerequisites
Research it when Musketeers will defend a position or remain in a sustained engagement where the added durability matters. For a mobile attack or map rotation, account for the slower movement and pair the line with faster units for scouting and screening. The health bonus cannot compensate for being unable to disengage or reinforce in time.
How the effect changed across updates
The Church technology has had different target classes and a larger movement penalty in earlier rules. Before update 13.690, its hit point bonus applied to Heavy Infantry; update 13.690 broadened that health bonus to Infantry. Update 13.27885 reduced the movement penalty from 25% to 10%, and update 14.43676 narrowed the health effect to Musketeers. The current profile is therefore +20% Musketeer hit points and −10% speed. Do not combine the older class coverage or 25% penalty with the current values.