The microstructure of chain-mail (CM) armor consists of a network of small links that are connected together to form a sheet. A network-type model, amenable to straightforward numerical simulation, is formulated, where the links are modeled as supporting only axial (tensile) loading, and where the interconnections are idealized as threedimensional frictionless pin-joints. Because of its use as a ballistic shield, the strain-rate dependent thermo-mechanical (viscoplastic) response is important, due to thermal softening. The philosophy behind the proposed direct modeling approach is to harness the dramatic increases in readily available scientific computing to simulate realistic responses of structural CM, by starting directly at the microscale, where relatively simple description of the material is possible. By employing enough of these simple structural elements, one can build an entire macroscale sheet of CM. The deformation of the CM is dictated by solving a ("link-coupled") system of differential equations for the motion of the interconnected masses. Large-scale simulations, illustrating the thermomechanical response of chain-mail material armor, undergoing impact with a rigid indenter, are presented to illustrate the potential of the approach in delivering realistic responses, involving dynamic rupture and penetration of structural CM.1 Introduction. We consider materials with microstructures known as "chain-mail" (CM) armor that is made from chain or chain links, woven together to form a flexible "metal fabric". Since chain-mail is intended to protect against concentrated impact by redistributing the load in the contact zone, we concentrate on blunt impactors. There are many types of CM, all of which have a basic common underlying structure, namely, chain links that are connected together to form networks of chains and, ultimately, sheets. These patterns can be quite elaborate, however, in this paper we will concentrate on the most basic rectangular grid-like structure (Figure 1). The structure can be idealized as a network of small pinned-end links that take purely axial tensile loading, and nothing in compression (since the links slide relative to one another in compression). A key aspect of our approach is that if the properties of the links are known, the structural scale (sheet-level) properties can be constructed, without resorting to phenomenological parameters. For most types of structural CM, the overall rupture of a single link is gradual, as opposed to abrupt, due to plastification within the links. An important feature of the direct modeling approach is the ability to directly incorporate the plastification and rupture of each metallic link into the structural scale response of the CM.A reduced-order model is constructed by combining a link-network representation with dynamic discrete/lumped masses. The deformation of the CM is dictated by solving a coupled system of differential equations for the motion of the lumped masses, which are coupled through the links. Quantitative numerical simulations...