Moscow was occupied by Napoleon's Army.

Summary: The text mentions that "The cathedral could disappear during Napoleon's invasion." This implies that Napoleon's Army was in Moscow and that the cathedral was potentially threatened.

Detailed analysis: The sentence "The cathedral could disappear during Napoleon's invasion" directly links Napoleon's invasion to Moscow, as the cathedral is located in Moscow. While it doesn't explicitly state "Moscow was occupied," the context of an invasion and potential disappearance of a landmark strongly suggests occupation or at least a significant military presence.

Conclusion: This statement is TRUE based on the provided text.