In the fourth
Progress Level, the theoretical knowledge of the previous era matures into widespread practical application. The harnessing of hydraulic, steam, and electric power creates an explosion of commerce and industry. Developments such as the telegraph, the telephone, and the radio make true global communication possible. Breakthroughs in manufacturing techniques allow the construction of heavy ironclad vessels, rail transportation, and architecture of previously unimaginable size. Pioneers venture high into the atmosphere and descend into the sea's depths.
Urbanization is complete as individuals gather in smaller environments where they can more easily exchange goods and information. Corporations expand in power, many establishing themselves throughout the explored world. Governments are based on political and economic factors.
The means of war change swiftly through the period. Aircraft and submersibles join the list of
military assets. Reliable and accurate rifles, pistols, and machine guns become common. Mechanized war machines herald the first great change in the art of battle since the end of the knight.