We introduce an analytical study of the links between macroscopic strength and the grain-to-grain interactions in two-dimensional frictional granular packings. This study consists of two main parts that are developed and connected progressively. First, we obtain explicit expressions that enable us to relate microscale parameters such as contact forces and fabric to macroscopic stress and strength. Second, physical connections and interpretations between the aforementioned micro-parameters, micro-mechanisms, fabric anisotropy and macroscopic strength are derived. Furthermore, throughout this theoretical study, some fundamental physics related to a packing’s strength as well as contact buckling is extracted, providing a better understanding of the micro-mechanics that furnishes and builds up the macroscopic strength of this kind of materials.