October 16, 1944 Red Army 9th "Sappers" noticed that they have crossed the Soviet border and stepped into German territory. In Eastern Prussia shoulder to shoulder with the infantry and tank crews were soldiers and officers of the engineering troops who helped storm the enemy positions, roads, render ineffective minefields, build the crossing, bridges and airfields. Awaiting them was a huge amount of hazardous waterways, through which the Germans had destroyed bridges. Sappers were to conduct engineering and reconnaissance in the rivers, finding fords, through which the T-34 could cross. Liberators went to Konigsberg. The city, blocked from the north, east and south, the north-west was held by German troops on the Samland Peninsula. Strengthening Konigsberg consisted of external and internal zones of defense. Forts erected as early as the mid-nineteenth century by German engineers were turned into a truly impregnable fortress. Front line of defense entirely covered by minefields.