The decision to start construction of the naval fortress line came after the disastrous events at Tsushima, where the whole Russian Baltic Fleet had been annihilated. The road to Saint Petersburg was then unprotected and open. The quickest and cheapest way of dealing with this problem was to protect Saint Petersburg with a seemingly impenetrable zone of coastal artillery until a new fleet had been constructed. The idea was presented for the first time in 1907. Czar Nicholas II approved the plans on July 5, 1912, and the construction began soon thereafter.