In October 1951, Chicago fell under a massive Spire attack and infecting the city within a fifty mile radius. Although declared a gray zone, Chicago saw little Chimeran activity in the growing months and was considered contained. However, in April 1952, SRPA reported of Chimeran forces amassing inside Chicago and preparing a likely assault on the northeast section of the Liberty Defense Perimeter. Given that the LDP is only suited to withstand an attack by airborne Chimeran battleships, but it is not equipped to hold back a large scale ground assault. SRPA dispatched Specter Team in eliminating the growing Chimeran presence.
On April 22, 1952, Specter Team managed to contain the Chimera in Chicago after decimating the Chimeran command structure, seizing key strategic locations, and eliminating much of the Chimeran infrastructure in the city. The result was a major blow to Daedalus' strategy in the United States in which Chimeran forces, having been inflicted with heavy casualties, were in no position to mount a ground attack on the Liberty Defense Perimeter.
Alongside Specter's objectives, SRPA Recon Team X-Ray infiltrated the Chicago Tower and discovered the existence of seven other Chimeran towers in the United States, six of which were previously unknown. It is this discovery that the Chimera intended on excavating these towers as part of their goal of reactivating the tower network.
- Shadow Strike takes place right around thirteen months before Echo Team arrive in Chicago.