Warre wuxuu ka qeybgalay Royal Military College, Sandhurst xagaagii 1807 waxaana bishii May ee soo socotay loo magacaabay "aide-de-camp" Major-General Sir Ronald Craufurd Ferguson. Dhowr bilood ka dib, Warre wuxuu ku laabtay waddankiisii hooyo ee Portugal, halkaas oo uu ku arkay dagaalkii Roliça
(17 Agoosto) iyo Vimeiro (21 Agoosto) ka hor inta uusan ku xanuunsan cudurka shuban biyoodka. Waxaa loo diray inuu ku soo kabsado Lisbon, halkaas oo Major-General William Carr Beresford uu ku soo dhaweeyay gurigiisa. Ka dib markii uu soo kabsaday, Beresford wuxuu Warre ku soo bandhigay shaqaalihiisa wuxuuna u adeegay dhammaan ololihii Sir John Moore, isagoo ku dhammaaday Dagaalkii Coruña bishii Janaayo 1809.