Princess Kate marks her 43rd birthday today.

The British royal has just come out of a “difficult” year following her diagnosis and treatment for cancer. In a heartfelt birthday message shared on Instagram, her husband, Prince William, commended Kate’s “strength.”

William posted a touching black and white image of Kate, writing, “To the most amazing wife and mother. The strength you’ve demonstrated over the past year has been incredible. George, Charlotte, Louis and I are so proud of you. Happy Birthday, Catherine. We love you.”

The image features Kate dressed in a light button-up shirt, dark jeans, a shepherd check scarf, and a dark coat.

During a Christmas concert in the U.K. last month, Kate opened up about her challenging year. She mentioned to singer Paloma Faith, one of the performers at the event, “I didn’t know this year would turn out to be what it has.”

The intense public scrutiny regarding her absence led her to reveal her cancer diagnosis. In March, Kate disclosed that she would begin a course of preventative chemotherapy following abdominal surgery. After her treatment concluded in September, she shared a video on social media stating, “My journey to healing and complete recovery will take time, and I must take life one day at a time.”

As she heals, Kate has made more public appearances, including attending the Trooping the Colour parade, Wimbledon, various church services, and her traditional Christmas carol service. At the latter event, she spoke about unity and acknowledged “our own vulnerabilities” during the festive season, emphasizing the importance of empathy.

Kate expressed, “When we take a moment to step away from our daily pressures, we allow ourselves to live open-heartedly, embracing love, kindness, and forgiveness—this is the essence of the Christmas spirit.”

“The Christmas narrative encourages us to acknowledge others’ experiences and feelings. It reflects our own vulnerabilities and highlights the need for both giving and receiving empathy and how crucial we are to one another, regardless of our differences. Above all, it inspires us to choose love over fear.”