What does the word "wave" used in this context mean?
Native speaker’s answer
Rebecca
The word "wave" in this context is similar to stage or step, with heavy force. The first "wave" would be their first invasion. Then maybe they'd drawback and get ready to invade again for the second "wave". Ex: We had a sale today. The first wave of customers came in at lunchtime. The second wave came in the afternoon. Ex: A wave of happiness suddenly came over me. Then I was sad again.