The COVID-19 pandemic has put unprecedented pressure on teachers around the world, raising significant concerns about their workload and wellbeing. Our comparison of 2019 (pre-pandemic) and 2020 (first year of the pandemic) survey data (n = 362) from teachers in New South Wales, Australia, demonstrates that their morale and efficacy declined significantly during COVID-19, even with the relatively short period of school closure (8 weeks) during 2020. Interviews with teachers and school leaders (n = 18) reinforced these findings and highlighted the depth to which teachers felt dispensable and unappreciated, despite working incredibly hard for their students. The pressure to adapt to online teaching and learning, in trying circumstances, also challenged their confidence in their teaching. We argue that practical and emotional support for teachers both during periods of remote learning and upon students' return to the classroom is essential to support teacher's wellbeing and a robust teaching workforce into the future.