What to expect
A monument says more when you know who is being remembered. Campo de la Alianza commemorates the 1880 battle and its Peruvian and Bolivian participants. Read a little about the war beforehand and take the interpretation seriously without mistaking one national account for the whole story.
How it fits into a journey
Make it a focused excursion from Tacna, then return to the centre. There is no need to add three more compulsory stops.