The presence of sufficiently large enemy fleets at a colony will prevent all construction at that colony. A Larger colony will require larger fleets to be blockaded.

• Buildings can no longer be destroyed or built.
• Ships can no longer be constructed.
• Ships should be unable to be bought or sold on the market.

• You must declare war on the enemy colony owner.
• Offensive weapons are required on a ship.
• Gun batteries greatly enhance the effectiveness of a capship's blockading power.
• Tonnage matters (most likely).

When your fleets attempt to enforce a blockade, you will be notified of the fleets power. An estimate of "LOW" indicates that your fleet's blockading power is very minuscule, regardless of the colony.

An actual number displayed will indicate the blockade's power as compared to the victim colony.

Fully armed destroyers are a very capable ship for blockading. As a rough comparison between blockading power, 4 destroyers = 15 CCs = 750 bombers.