On the night of November 4, in main parts of Germany, France, Italy, Belgium, Spain, and Portugal, over 15 million households were left without power after a cascading breakdown of the 2006 European blackout. Power grids of several other nations (Belgium, Netherlands, Poland, Switzerland, Czech Republic, Greece and Morocco) experienced minor local outages. The root cause was an overload triggered by the German electricity company E.ON switching off an electricity line over the river Ems to allow the cruise ship Norwegian Pearl to pass through safely. The impact of this disconnection on the security of the network had not been properly assessed, and resulted in the European transmission grid splitting into three independent parts for a period of two hours. The imbalance between generation and demand in each section resulted in the power outages for consumers.