Artists in the context of Nazi Germany

1. Does "artists in the context of Nazi Germany" mean "German Artists during Nazism" or "artists whose works were about Nazi Germany"?

2. Does "what was essentially at stake in both of these historical contexts" mean "what was not considered and not paid attention to in both of these historical contexts"?

3. Does the last sentence mean "The imagery and texts used needed to be straightforward and explicit and deliver short incisive messages, just like in advertising or propaganda, but they were not"?

Context:
In effect, the relationship of the Docklands posters with the historical avant-garde extended beyond practices associated initially with the USSR to those developed by politically radical artists in the context of Nazi Germany. However, what was essentially at stake in both of these historical contexts, as well as in the Docklands poster campaign, was the need to communicate quickly and effectively. The imagery and texts used needed to be straightforward and explicit, delivering short incisive messages, in the manner of advertising or propaganda (Art and Advertising by Joan Gibbons).