Their final destination was often a death camp

In attempting to unravel how this was achieved, Professor Mark Roseman traced the final journey of Ernst Krombach and his family, German Jews deported from Dusseldorf to Lublin in Poland in the spring of 1942.

In retracing their last journey to a holding ghetto in the village of Izbica - a dark journey taken by many thousands of Jews during World War Two - he took in the railway line that came to symbolise the ruthless efficiency and seeming omnipotence of the Nazi state.

Ruthless efficiency

This journey - and hundreds of others like it - was not the rushed, desperate action of an irrational regime. Instead it was a part of a well thought-out and meticulous plan, steeped in bureaucracy and paperwork and executed with a ruthless efficiency.

More importantly it was seemingly carried out under the noses of large swathes of the population of Germany.

The particular deportation that Professor Roseman followed had begun six decades earlier at Dusseldorf Station on a bright Tuesday morning in April 1942, where up to 1,000 Jews were herded onto a train.

It was a place where they would have been seen by many people, but how many onlookers knew the final destination of those trains?

Pay for their own fate

The Nazis' task of identifying and rounding up the Jews was made easier by the fact that the registry offices recorded the religious identity of all citizens.

Memories of the Holocaust run deep

And the rare documents that Professor Roseman unearthed in the SS archive showed that there were strict instructions on just how to identify and then evacuate the Jews.

The documents showed how nothing was left to chance, including giving detailed instructions of what the deportees were allowed to bring with them and what to tell the town councils when people left town.

There were even guidelines on how to seize bank accounts in order to pay for the whole operation - meaning that the Jews unwittingly paid the bill for the holocaust with their own life savings.

The ruthless efficiency of the final solution is also demonstrated in the actual train journey.

The authorities had worked out a way to timetable the trains so they did not hold up the normal flow of public transport in the rest of Germany.

Into the unknown

The trains used to transport the Jews to Poland were the same trains that had shipped forced Russian labour into the country. They had simply been cleaned up and turned around to head for Poland.

Don't be worried, if it carries on like this - we can all be content

Ernst Krombach's letter from the train

But just as the onlookers had no idea of the destination for this fatal journey, many of those on the trains were also unaware of their grisly fate.

Love letters smuggled from a train by a young Jew, Ernst Krombach, to a sweetheart left behind in Dusseldorf, show that he really did not know his fate; he really did not know he was heading to a death camp.

His letters were full of pragmatism and suggested that spirits on the trains were buoyed and not broken by the fact that they were going to Izbica.

One letter he wrote said: "I found out by chance that we are going to Izbica. More definite information I don't have at the moment. Don't be worried, if it carries on like this - we can all be content."

Within three months of writing those words, he, his family and all of those on the train were dead. The Nazi machinery had run like clockwork.