<p>This study investigates the active earth pressure exerted on a battered retaining wall, often referred to as a hunch-backed wall, supporting unsaturated backfill. The analysis employs the horizontal slice method and a unified effective stress approach, incorporating one-dimensional vertical flow to account for unsaturation effects. A parametric study was conducted for both cohesive and cohesionless backfill materials, examining variations in (i) the geometry of the hunch-backed wall, (ii) the position of the groundwater table, and (iii) flow conditions. The results show that incorporating a hunch at the back of the wall reduces active earth pressure by approximately 27% for cohesionless backfill and 52% for cohesive backfill compared to a vertical wall. Notably, for cohesive backfill, the hunch has a more significant effect on earth pressure under no-flow conditions than under infiltration or evaporation scenarios. The distribution of active earth pressure and failure patterns obtained from the analysis are consistent with previously reported studies.</p>