Powers, especially among Czechs, Poles, and Arabs. In addition, there were multiple peace proposals coming from neutrals, or one side or the other; none of them progressed very far. Legacy and memory The first tentative efforts to comprehend the meaning and consequences of modern warfare began during the initial phases of the war, and this process continued throughout and after the end of hostilities, and is still underway, more than a century later. As late as 2007, signs warning visitors to keep off certain paths at battlefield sites like Verdun and Somme remained in place as unexploded ordnance continued to pose a danger to farmers living near former battlegrounds. In France and Belgium locals who discover caches of unexploded munitions are assisted by weapons disposal units. In some places, plant life has still not returned to normal. Historiography Teaching World War I has presented special challenges. When compared with World War II, the First World War is often thought to be "a wrong war fought for the wrong reasons". It lacks the metanarrative of good versus evil that characterizes the Second World War. Lacking recognizable heroes and villains, it is often taught thematically, invoking tropes like the wastefulness of war, the folly of generals and the innocence of soldiers. The complexity of the conflict is mostly obscured by these oversimplifications. George Kennan referred to the war as the "seminal catastrophe of the 20th century". Historian Heather Jones argues that the historiography has been reinvigorated by the cultural turn in recent years. Scholars have raised entirely new questions regarding military occupation, radicalisation of politics, race, medical science, gender and mental health. Furthermore, new research has revised our understanding of five major topics that historians have long debated: Why the war began, why the Allies won, whether generals were responsible for high casualty rates, how the soldiers endured the horrors of trench warfare, and to what extent the civilian homefront accepted and endorsed the war effort. Memorials Memorials were erected in thousands of villages and towns. Close to battlefields, those buried in improvised burial grounds were gradually moved to formal graveyards under the care of organisations such as the Commonwealth War Graves Commission, the American Battle Monuments Commission, the German War Graves Commission, and Le Souvenir français. Many of these graveyards also have central monuments to the missing or unidentified dead, such as the Menin Gate Memorial to the Missing and the