German fuel dependence before the diesel-fleet question

Fuel security sets the limits of the diesel-fleet scenario. Germany had limited domestic and synthetic production, while oil also arrived from Romania, the Caribbean, the United States, the Soviet Union, and Mexico. Estimates cited here put the tanker-borne share of German oil supply at 63 to 72 percent in the mid-to-late 1930s. That dependence left the supply vulnerable to maritime interdiction before any propulsion choice came into play. A navy designed around a different fuel still faced the strategic problem of where that fuel came from and how it reached Germany.