In 1948, he pretended to be an Arab fighter and observed Israel's War of Independence - from the Arab side. His observations were published in 1951 as "Cairo to Damascus." You can read most of the book online here, and it is fascinating. For example, he writes about dinner with London anti-semite, Nazi admirer and Arab supporter Robert Gordon-Canning:
It turns out that Carlson has an unpublished manuscript from right after the war, and JStreetJive has part of it. Here is some of what they have published so far, from his interviews of Arab refugees in UNRWA camps:
Follow the rest at JStreetJive.