Prior to the D-Day invasion in June 1944, the greatest invasion up to that time, in man power and might, was the Allied September 1943 landing in Italy.

British intelligence officer Norman Lewis served in the American Fifth Army as it made its way up from the Amalfi Coast to Naples, where he was stationed for a year as an interpreter between the military and the civilians. Director Francesco Patierno adapts Lewis’s 1978 poignant and picturesque memoir into an impressionistic documentary. The day-to-day anecdotes converge into a vital and fragmented account of life immediately after wartime. The time-traveling visuals are gracefully propelled by Benedict Cumberbatch’s narration of Lewis’s eloquent and precise prose, with its sotto voce observations intact (“Neapolitans take their sex lives very seriously, indeed.”). Much of the treasure trove of contemporaneous footage is from London’s Imperial War Museums.

When Lewis entered the city, it “smelled of charred wood, with ruins everywhere.” Reenactments, sporadically featured, roughly hint at or give a visual snapshot of what Lewis captured in print. The former capitol of the Kingdom of the Two Sicilies had a population of nearly a million and was without running water; its infrastructure was damaged during Allied bombing when the city was under German control. Food was scarce—Lewis reports the cat population plummeted. Typhus and small pox were rampant, and to make matters worse, Mount Vesuvius erupted in February 1944. (Not mentioned: Naples was the largest city anywhere in which citizens and the Italian Resistance overthrew the German occupiers.)

Most of the indelible images from the book are echoed here: Lewis’s account of stumbling upon the three 2,500-year-old Greek temples at Paestum; women lining up against the wall in a piazza bartering sexual services for food; and his newfound friend, who earns food and money posing as the haughty “uncle from Rome” at funerals.

The director steers clear of clichés with an atypical soundtrack selection. Not too surprising, an operatic score plays in the background, but it’s Tchaikovsky’s Eugene Onegin, and not Cavalleria Rusticana. Like Patierno’s earlier documentary, the delightfully dishy The War of the Volcanoes, he has made a tribute to postwar Italian Cinema, which was arguable Italy’s most internationally noted export from the 1950s through the ’60s. The earlier film centered on two dueling and entangled film projects in 1949: Volcano, with Anna Magnani; and Stromboli, directed by Magnani’s former companion (and collaborator) Roberto Rossellini, starring Ingrid Bergman, who was to become his wife. Scandal and denunciation on the floor of Congress followed.

Here, Patierno lavishly punctuates Naples ’44 with films emerging from the so-called neorealism style of filmmaking (Rossellini’s Paisan), the 1950s through the 1980s, as well as Mike Nichols’s Catch-22 (1970). That film is perhaps the most relevant of the selections, given its depiction of an American GI falling in love with an Italian sex worker. Viewers will spot Ernest Borgnine in Vittorio De Sica’s The Last Judgment (1961) and Marcello Mastroianni in Liliana Cavani’s The Skin from 1981.

The evocative film also doubles as an apertivo, as it premieres at New York’s Film Forum shortly before the theater kicks off its film series “Roman Hollywood: American Movies Go to Italy,” centered on international productions made in Rome’s Cinecittà studios and its environs. Besides the tried and true Roman Holiday, Quo Vadis, Ben-Hur, and Summertime, it will screen the not-available-on TCM, The Pirates of Capri.