It was not the speech Joe Biden wanted to give—at least not this year, under these circumstances. But if anyone knows how quickly fortunes can change, it’s this president, whose personal and professional life has been scarred by tragedy and adversity.

Speaking to a packed arena in Chicago on the first night of the Democratic National Convention, Mr. Biden offered a full-throated defense of his presidency, touching on many of the themes he campaigned on in 2020 and again this year before abandoning his re-election bid in mid-July, just a few weeks after a catastrophic debate performance.

“Like many of you, I gave my heart and soul to this nation,” he said toward the end of a nearly hour-long address punctuated by raucous shouts of “Thank you, Joe.”

Mr. Biden had walked onto the stage after being introduced by his daughter, Ashley, and his wife, Jill, who told the audience she “saw him dig deep into his soul” when he decided to exit the presidential race. After hugging Ashley, he put a tissue to his eyes to dab away the tears.

The president touched his heart and stood a little straighter at the lectern, flashing a toothy smile as the crowd continued to cheer.

His speech was keenly aware of his place in history, but he also spent time singing the praises of his vice-president—the woman he hopes will succeed him in the White House