1747, Rapin de Thoyras, The History of England, Volume XXII, James and John Knapton, page 408:
It is now, Holy Father, your business to accompany him by 1707-8. colours and standards were, Dieu & mon Droit, "God and my Right:" Nil desperandum Christo duce & auspice Christo, "I ought not to despair, since Christ is my guide and helper:
Nil desperandum Teucro duce et auspice Teucro (there is nothing to despair about with Teucer as our leader and Teucer as our protector). —Horace, Odes, I.vii.27 (translation Benham's Book of Quotations).
never despair.
I am not going to give up. Not for giving up, as in: this is not for giving up on.
Etymology
Latinnīl ‘nothing’, dēspērandum, gerund of dēspērāre ‘despair’, as used in Nil desperandum Teucro duce at auspice Teucro ‘no need to despair with Teucer as your leader and Teucer to protect you’, in Horace, Odes