Generally it is believed (especially by British historians) that one of the major reasons that the League of Nations failed was that it did not have its own army, like the United Nations does today. It is believed that without this there was no true negative impacts for countries that broke international laws and treaties. When it comes to achievements and failures this is very dependant on who is asked. Many feel that Abyssinia was the major failure (http://www.historylearningsite.co.uk/modern-world-history-1918-to-1980/italy-1900-to-1939/abyssinia/), however others argue that this was an attempt to keep the peace, and not throw the world back into another world war. There was another failure in the form of the Manchurian crises (http://www.bbc.co.uk/schools/gcsebitesize/history/mwh/ir1/manchuriarev1.shtml) which was largely ignored by Western countries, due to its distance and lack of links to the area. There were no sanctions the League of nations could put into effect except for trade sanctions, however if these were ignored there was little they could do. The achievements included Aaland Islands dispute between Finland and Sweden also the Greek attack on Bulgaria in 1925, unfortunately I do not know about this in detail. There was also a lack of countries involved in the league of nations, most pronounced of these was the US who although it was one of Woodrow Wilsons 14 points, did not join, and without the power bought in by the US at the time it always seemed deemed to fail as Europe was in a very poor position after the first world war. (http://www.thestudentroom.co.uk/wiki/Revision:The_Achievements_and_Weaknesses_of_the_League_of_Nations)