The book of Colonel-General Grechko A. A., Commander of the First Guards Army: "Across the Carpathians", gives detailed pictures about the fights of the 4. Ukrainian Front in the Eastern Carpathian Mountains from August to October 1944. So, I can introduce the operation of the Árpád-Line, this forgotten Hungarian fortification system from the point of view of that Army Commander who wanted to capture it. Let us see, how general Grechko saw that theatre of war, where he had to attack: "…There are many smaller or larger rivers and streams in the valleys and ravines of the Eastern Carpathians, which divide the mountains in different directions. Because of this dismemberment several blocks of mountains came into being, their length may be 10-12 kilometres. Although the Carpathian rivers are usually shallow, their large number, their steep banks, and the separate mountain ranges, valleys and ravines made the Carpathian Mountains almost inaccessible for troops and mechanised military equipment. The majority of the slopes of the mountain ranges and the forests covering the mountains also made the movements and activities of the troops extremely difficult. (Page 65.) So, the Carpathian Mountains meant enormous and complicated natural obstacle for our troops on the routes of advance. The possibilities of passing them were restricted by the fact that there were comparatively few passes with routes for trucks, coaches, or railway. The infantry could cross the Carpathians in almost all directions on the mountain paths with its arms - even with machine-guns and with mine throwers transported on pack animals. But the trucks, jeeps, tanks and artillery could advance only on the roadways. These corps of arms could advance on other kind of routes only in dry weather. In certain sections the light and middle calibre artillery followed the fighting order of the infantry not only across the most important passes.. Their units surmounted the natural obstacles of the mountains by the help of the infantry and engineer troops, advancing on earth roads and on tracks (Page 107).