As I write my February blog, Sir Anthony Beevor, historian and bestselling author of epics such as “Berlin” and “Stalingrad”, is talking on Radio 4’s Desert Island Discs. I am humbled by his ongoing questioning of the facts in spite of his already huge achievements in bringing World War 2 to life in extraordinary detail. And I’m grateful for his admission of how hard it is to research this horrendous episode of history. His voice wobbles as he talks of reading the gruesome accounts of the rapes, murders and infinite human suffering. “We write to understand,” he says, emphasising the necessity for us to “learn the lessons of history”.

For years now, I too have been staring into the darkness of German history, the soil in which half my family’s roots reside, trying to understand what happened, how something like Nazism and the Holocaust could have happened. I read and read and watch endless footage, like a detective piecing together the evidence from a crime scene. I don’t have any need to blame or justify, I just find my eyes straining in their attempts to make out the outlines of some kind of meaning to it all, for anybody.

Germany as a nation has heaved itself out of the rubble, brushed itself down and with cap in hand has apologized, over and over again. And now the shroud of silence in which post-war Germans wrapped themselves with a stubborn “We knew nothing”, is also finally being shed in painful spasms as more and more grandchildren excavate their family stories in search of the truth. In his brilliant new book The German War: A Nation Under Arms 1939-45, Nicholas Stargardt dispels the myth of total ignorance of what was going on once and for all by gently revealing the inner thoughts of German soldiers and civilians as expressed in their letters and diaries. For many people, however, it is still too painful, too shameful, to go anywhere near their past and I can totally appreciate why.

Writing my book is without doubt one of the hardest things I’ve ever done. For months now I have been living in the sepia world of the 1940’s, digging down like a miner into the bloodied soil of Germany’s past to retrieve the shards of its shattered reality. Each time I come up for air I have to adjust my eyes to the bright lights of 2017, re-learn how to laugh and talk and enjoy. But like the Sunday evening of a weekend home from boarding school, the impending descent back into the mineshaft looms, until I climb down the ladder and re-enter the blackness once more, waiting for my eyes to adjust before I can continue my work.

It is indeed painful work. It challenges family loyalties threatening to expose the wounds around which new lives were built, like barbed wire absorbed by tree trunks on their way to the sky. It hurts to question the thoughts and actions of your own much-loved grandparents in those impossible times, to grasp what decisions they were faced with and to accept their possible fallibility. I don’t want to be the surgeon that rips off the bandages that held their psyches together, for I too am on the operating table, and yet the promise of understanding, of learning the lessons of the past, and of healing both generations, overrides everything, like the promise of gold urges the miner to keep on digging.