The origin of our style of sesshin

Because zazen is so central to our practice, we might assume that sesshin is an ancient tradition. Like several other familiar elements of our practice, such as kinhin, it's really only been around for four hundred or five hundred years, when Japanese temples began engaging in sesshin in order to spend some focused time on zazen. Generally, activities such as work periods and long morning services are set aside so that that time can be redirected to zazen. The life of the temple must go on, so the day still includes liturgy and other basic functions, and perhaps some teachings. This kind of day looks similar to what happens during sesshin in a dharma center in North America, but it's not what Sawaki Roshi and subsequently Uchiyama Roshi wanted to do.
Sawaki Roshi was ordained as a novice at the end of the 19th century. He had been practicing at Eiheiji, but he saw that zazen was not the central activity of the day there and made arrangements to stay instead in an abandoned temple in Nara. Entering and closing the gate, he sat by himself for two or three years. He had to go off to fight in the Russo-Japanese War in the early 1900s, and after the war he returned to his practice and to the study of the Shobogenzo. By 1935 he was teaching zazen at Kanazawa University.
The style of sesshin we do at Sanshin began in the 1940s, when Sawaki Roshi practiced at Daichoji. He was not always in residence there, but he came once a month for a standard sesshin, which probably included liturgy, meals using oryoki, a dharma talk and a work period. Many people from outside the temple came to participate. When Sawaki Roshi was away, however, the residents of the temple held a second monthly sesshin for themselves which only included sitting. During this sannai (inside the temple) sesshin, sitting went on 24 hours a day. The day began at 2 am and followed a familiar pattern of 50-minute zazen periods and 10-minute kinhin periods until midnight. After that time, until 2 am, there was no kyosaku and the residents could sleep while sitting on their cushions. This was the first place where Uchiyama Roshi practiced, having been ordained as a novice in 1941, and he stayed until 1944, when the residents had to leave the temple during World War II. They didn't have a consistent place to practice until 1948, when they settled at Antaiji.
Antaiji had been founded in 1920 by Oka Sotan, who, among other things, served as the president of Komazawa University and a director at Eiheiji. It was re-established with funding from a former Soto Zen clergy turned successful businessman as a place for Komazawa graduates to study Dogen's teachings. With those funds no longer available due to the war, the temple was empty and thus available to Sawaki and his disciples. Antaiji had no lay members and thus no regular donations. Nonetheless, two monthly sesshins went on as usual, one with Sawaki Roshi and one without.
Eventually, Uchiyama Roshi took over leadership of Antaiji, and began to modify his teacher's sesshin schedule. To protect their wellbeing, participants now slept from 9 pm to 4 am and on that basis were expected not to sleep during zazen. As had happened with Sawaki Roshi, many people came from outside to participate. The usual dozen or so residents were joined by as many Japanese laypeople and as many again foreigners living in the area. This is the sesshin that Okumura Roshi engaged in while living and practicing at Antaiji, and the style that he vowed to transmit to us in North America.
Sawaki Roshi was ordained as a novice at the end of the 19th century. He had been practicing at Eiheiji, but he saw that zazen was not the central activity of the day there and made arrangements to stay instead in an abandoned temple in Nara. Entering and closing the gate, he sat by himself for two or three years. He had to go off to fight in the Russo-Japanese War in the early 1900s, and after the war he returned to his practice and to the study of the Shobogenzo. By 1935 he was teaching zazen at Kanazawa University.
The style of sesshin we do at Sanshin began in the 1940s, when Sawaki Roshi practiced at Daichoji. He was not always in residence there, but he came once a month for a standard sesshin, which probably included liturgy, meals using oryoki, a dharma talk and a work period. Many people from outside the temple came to participate. When Sawaki Roshi was away, however, the residents of the temple held a second monthly sesshin for themselves which only included sitting. During this sannai (inside the temple) sesshin, sitting went on 24 hours a day. The day began at 2 am and followed a familiar pattern of 50-minute zazen periods and 10-minute kinhin periods until midnight. After that time, until 2 am, there was no kyosaku and the residents could sleep while sitting on their cushions. This was the first place where Uchiyama Roshi practiced, having been ordained as a novice in 1941, and he stayed until 1944, when the residents had to leave the temple during World War II. They didn't have a consistent place to practice until 1948, when they settled at Antaiji.
Antaiji had been founded in 1920 by Oka Sotan, who, among other things, served as the president of Komazawa University and a director at Eiheiji. It was re-established with funding from a former Soto Zen clergy turned successful businessman as a place for Komazawa graduates to study Dogen's teachings. With those funds no longer available due to the war, the temple was empty and thus available to Sawaki and his disciples. Antaiji had no lay members and thus no regular donations. Nonetheless, two monthly sesshins went on as usual, one with Sawaki Roshi and one without.
Eventually, Uchiyama Roshi took over leadership of Antaiji, and began to modify his teacher's sesshin schedule. To protect their wellbeing, participants now slept from 9 pm to 4 am and on that basis were expected not to sleep during zazen. As had happened with Sawaki Roshi, many people came from outside to participate. The usual dozen or so residents were joined by as many Japanese laypeople and as many again foreigners living in the area. This is the sesshin that Okumura Roshi engaged in while living and practicing at Antaiji, and the style that he vowed to transmit to us in North America.