I watched this late last night on BBC Two - WW1's Secret Shame; 29 days left to watch it on BBC iplayer.

Dan Snow explores the challenge presented by an ongoing mental health crisis among war veterans. He discovers how the shell shock of WW1 has evolved into the cases of PTSD that modern soldiers suffer with today.

Shockingly, lessons learnt from previous conflicts were soon forgotten. Battle trauma leads to alcoholism, broken families, violence and suicide on a shocking scale in the UK. He asks military psychiatrists and experts why we're still struggling to help the psychiatric casualties of war.

Dan shares frank and moving conversations with veterans of World War Two, the Falklands and Afghanistan, and also with relatives of those who fought in World War One.