after crimean war fortifications of viapori were improved by building artillery casemates and new bomb-proof buildings. vallisaari just east of suomenlinna was the site of the first new construction works. the harsh suppression of the polish january uprising of 1863 and the resulting criticism soured the relationships between russia and western europe and hastened the fortification works. between 1863 and 1864 redoubts were built on vallisaari, kuninkaansaari and santahamina islands. in 1860s and 1870s russia purchased and then built under license new prussian krupp rifled breech loading guns which were also used in viapori. a total of 32 new bomb-proof stone powder cellars were built by the beginning of the 1870s, further improving the defences. the russo-turkish war of 1877–1878 was the next crisis that threatened the peace between russia and england, with new batteries being built at viapori on kuninkaansaari and older ones improved or rebuilt. new technology in the form of telegraph, railway lines and searchlights began to be used. improvements in artillery and ammunition forced improving the gun positions by covering the old walls and fortifications with a thick earthen walls. with high-explosive shells appearing at the end of the 19th century earth and stone were no longer sufficient and first concrete fortifications with steel doors were built in viapori. continually improving guns resulted increased range, necessitating rangefinders, while heavier guns and ammunition required improving piers, roads, cranes and ammunition carts to transport the guns or move ammunition from magazines to guns. despite the improvements the funds and resources allocated to the fortress were not sufficient to keep pace with the evolution of military technology. while parts of the fortress or were improved and new weapons or equipment were received, the overall condition of the fortress became ever more obsolescent, and the vulnerability of the flanks and rear were a lasting problem. by the end of 1880s and early 1890s viapori could no longer be considered a proper fortress but only a coastal position, capable of defending only against an enemy coming directly from the sea. the primary role of the fortress became more one of internal politics, as it helped the russians maintain control of helsinki.