Core Viewpoint - The initiative aims to collect valuable historical materials related to the "Little Third Line" construction and early civil defense projects in Shandong, commemorating the 75th anniversary of the establishment of the People's Air Defense in New China [1] Group 1: Historical Collection Focus - The collection focuses on three main directions: oral history from firsthand witnesses, written records of builders' experiences, and photographic documentation of the "Little Third Line" factories and civil defense sites [2][3] - The initiative seeks to gather original and heartfelt accounts from participants, witnesses, and those who heard stories about the era, emphasizing the importance of authentic and emotional narratives [2] Group 2: Submission Details - Participants are encouraged to submit their materials, including written documents and photographs, by July 31, 2025, to a specified email address, with clear instructions on how to title their submissions [3] - Each piece of collected material is viewed as an irreplaceable part of Shandong's national defense history, contributing to a richer understanding of the past and preserving the spirit of the era for future generations [3]