From ancient Jerusalem to today's urban battlefields in Ukraine and Gaza, we can find many examples of urban conflicts that have been heavily influenced by their underground components. But how should military forces categorize subterranean spaces and consider the different functions of underground structures? How does this subterranean dimension influence the conduct of military operations? What about the unique hazards of sending soldiers underground? And what are some of the planning considerations for attacking or defending subterranean positions? This episode addresses those questions and more in a comprehensive overview of underground warfare.

A strongpoint is a heavily fortified battle position tied to a natural or reinforcing obstacle. It is used to create an anchor for the defense or to deny the enemy decisive or key terrain. Throughout the history of urban warfare, buildings turned into strongpoints have played an outsized role. Multiweek battles have even been fought over single buildings used by the defender as strongpoints. In this episode, John Spencer is joined by Major Jayson Geroux, an urban warfare historian assigned to the Canadian Army Doctrine and Training Centre, and Mr. Stuart Lyle, the urban operations research lead for the UK-based Defence Science and Technology Laboratory, to discuss strongpoints on the urban battlefield.

What do engineers bring to urban operations? How do the basic capabilities resident in engineer units—like those in the US Army—enable maneuver forces to achieve their objectives when operating in cities? For commanders, what are the most important considerations to account for when employing engineers in combined arms operations, and what effects can they expect from specific engineer tactics and equipment? This episode examines those questions and more as John Spencer is joined by Lieutenant Colonel John Chambers, an engineer commander in the 1st Infantry Division.