It has always been my opinion that "Externalism" was very not-new, and that most of the best poets in history have been Externalists according to our definition. It was only in the last, unfortunate century that poets got away from the engagement with the real world we are trying to rescue through Externalism. To prove my point, and also to show that there are Externalists everywhere on all sides, I recommend The Selected Poems of Yehuda Amichai, translated by Chana Block and Stephen Mitchell. Amichai, 1924-2000, was the most celebrated Israeli poet of the 20th century, and for my money, one of the greatest poets who ever lived. As might be expected of an Israeli poet, he frequently grapples with such solid Externalist topics as war and cultural conflict, while simulaneously showing the effect of the same on human life and love. From the incredible "God Has Pity on Kindergarten Children":

God has pity on kindergarten children.
He has less pity on school children.
And on grownups he has no pity at all,
he leaves them alone,

From "Seven Laments for the War-Dead":

Mr. Beringer, whose son
fell at the Canal that strangers dug
so ships could cross the desert,
crosses my path at Jaffa Gate.

He has grown very thin, has lost
the weight of his son.

In the hands of these experienced translators and poets Amichai's poems come into English with something like the muscular power and sensual beauty they have in Hebrew. They aren't fancy, but they will nail you to the wall.

The Selected Poetry of Yehuda Amichai
Edited and Translated by Chana Block and Stephen Mitchell
University of California Press, 1996
ISBN-13: 978-0520205383