Themes
More than a third of the themes (37 or 38.9%) are related to warfare and military operations, intelligence service, and military equipment, which is consistent with the findings of our metadata analysis of personal names and organizations. The second largest category of themes (28 or 29.5%) focuses on various groups and activities, natural resources, street scenes, and landscapes. Another significant thematic category (17 or 17.9%) deals with historical events in China, Russia, and the United States, such as the Japanese invasion of Shanghai in 1932, the Panay Incident (1937), the Russian Revolution (1917-1921), and Pearl Harbor Attack (1941).
We attempted to demonstrate the diversity and frequency of the themes across various historical periods using an interactive stacked, clustered bar chart in Tableau Public. When you hover over or click on a section of the stacked bar in the chart, a pop-up window appears, displaying the thematic term, the time period associated with it, and the total number of related items in the digital collections. By dragging the bottom bar, you can view more thematic terms in the chart. This chart can be filtered further by selecting a time period from the legend in the upper right corner.
