THE IDEA OF OJANEN (Ojasen oivallus) – e5 sac in the Benoni
The e5 sac in the Benoni defence became famous by Penrose-Tal –game (7.11.1960). However, this was not the stem game. The e5 sac was originally invented by Finnish IM Kaarle (Kalle) Ojanen. GM Eero Böök calls this variant with the name ”The Idea of Ojanen” (in Finnish: ”Ojasen oivallus”) in his book Shakkipakinoita.
Kaarle Sakari Ojanen (4.12 1918 Helsinki – 9.1.2009 Helsinki) was a Finnish chess master. He was known as Charles XIII (Kaarle XIII) according to his 13 Finnish chess championships. His most famous game is probably the game against the Estonian GM Paul Keres 14.5.1960, where he played afore mentioned e5 sac. Kaarle Ojanen became International Master (IM) in 1952. Ojanen was technical leader by profession. He was interested among others in music and mathematics. Ojanen had honor to play 2008 (at the age of 90) two games against Sauli Niinistö, the Chairman of the Finnish Parliament (2007–2011) and the President of Finland since 2012. There are two games by Niinistö in chessgames.com (against WIM Johanna Paasikangas-Tella).
Ojanen himself regarded his game against Keres as his best game. Ojanen has said, that (in this game) he was able to use his own opening idea, which he had developed during a year. ”I won the game and after that I was like a winner in a big sports meeting. My opening idea got publicity and in a German magazine it was called the Attack of Ojanen... Soon the Russians presented antidotes to the opening so that it was not used a long time.” (http://www.shakki.net/artikkelit/galleria/ojanen_kaarle2.html)
Kaarle Ojanen playing with Sauli Niinistö:
Wikipedia-article on Ojanen