After a challenging year, Prince William has shared a moving tribute to his wife, Kate Middleton, on her 43rd birthday describing her as “the most incredible wife and mother,” alongside a new portrait.

The Prince of Wales shared a new picture and described his wife as 'remarkable' in a touching birthday tribute on Instagram.

Prince William praised his wife in a message shared to social media on her Jan. 9 birthday and posted a previously unseen photo of her by one of their go-to photographers, Matt Porteous. The black and white snap was taken in Windsor last summer and shows Princess Kate smiling as she looked into the distance, hands in the pockets of her jeans.

The black and white image depicted Princess Kate sporting dark high-waisted jeans and a crisp white shirt layered beneath a black blazer. All eyes however, fell on the royal’s choice of accessory. Princess Kate wrapped up warm in a checked scarf featuring a large gingham print and playful tassel trims.

Prince William penned a touching note to “incredible” Kate Middleton Thursday to celebrate her 43rd birthday, her first after finishing chemotherapy. The couple released Matt Porteous’ stunning black-and-white portrait of the Princess of Wales on their official Instagram account,

Kate Middleton is the saving grace of the monarchy in more ways than one. In addition to pushing through her cancer diagnosis and showing up at royal events while she received chemotherapy, the Princess of Wales has also played a pivotal part in keeping Prince William and King Charles 's relationship healthy during the royal family's recent challenging times.