The problem for Labour is that whenever they gain traction against the Tories, they are undone by their own failures. Just as it seemed that they may have mastered the narrative, strolls a smear story like no other: playing the man, as the ball has already been kicked off the pitch. Given the low-level of trust on defence, why did they think that smearing General Dannatt, a man who speaks up for Tommy Atkins, was a good idea
Perhaps there is anger at the usurpation of Labour's role. These politicians live in the Great War, believing that the officer corps sends soldiers to die and the politicians are there to protect the common poor bloody infantry. Except that the generals are perceived as the protectors and they are the donkeys. They prefer to shut the voice up that reminds them of their failure to live up to their supposed ideals.
But it won't hide the contempt that Labour felt towards the army and the needless deaths that resulted from the Ministry of Defence bottom-feeders that leapt upon that set of attitudes.