From the article:
Experiences fighting in Finland, especially against fortified positions left Soviet high command with the realisation that the Red Army desperately needed a tank capable of dealing with reinforced bunkers. Three design programmes were hurriedly put together with one successfully prototype completed in time to see action during the Finnish campaign.
The design mounted a modified 152mm howitzer into an enlarged KV turret and was referred to as ‘Dreadnought' by it crew. However, once it was adopted by the Red Army it was designed as the KV-2.