The choice of the new army chief, with his line of succession a subject of heavy speculation, looks likely to help Prime Minister Prayut Chan-o-cha consolidate his power and remain in the top seat at least until the next election.
Instrumental in picking assistant army chief Thirachai Nakwanich for the army chief post is Deputy Prime Minister and Defence Minister Gen Prawit Wongsuwon, dubbed the "big brother'' in the National Council for Peace and Order (NCPO), according to a military source.
Gen Thirachai, who will start working as army chief on Oct 1, has been chosen with future candidates for army chief visible.
The source said Gen Prayut needs to install men loyal to him who can keep the army politically stable.
Stability is the pre-requisite of Gen Prayut remaining in the premier's seat at least until early 2017 when the time is up for the NCPO to execute its roadmap of national administration and reforms and a general election is likely to be held.
But the business of finding a trustworthy choice of army chief, and his future successor, also fell to Gen Prawit who commands respect within and outside the army, the core of the armed forces' strength.
Gen Thirachai is replacing Gen Udomdej Sitabutr, concurrently deputy defence minister.
Assistant army chief Preecha Chan-o-cha, who is Gen Prayut's younger brother, has been promoted to defence permanent secretary, despite having been a contender for the army chief post.
Gen Thirachai will be the fourth army chief from the powerful Burapha Phayak army clique. The three former army chiefs from the clique are Gen Anupong Paojinda, Gen Prayut and Gen Udomdej.
The fraternity runs deeps as they all rose through the ranks before heading the 2nd Infantry Division, Queen's Guard, except for Gen Udomdej, who has not served as chief of the division.
Gen Thirachai graduated in Class 14 of the Armed Forces Academies Preparatory School (AFAPS) and he is due to retire September next year.
Although Gen Thirachai and Gen Udomdej are not close, Gen Udomdej decided to nominate Gen Thirachai who is known as one of Gen Prawit's proteges, according to the source. When Gen Thirachai takes the helm of the army, some senior officers close to Gen Udomdej could face transfers.
Meanwhile those connected to Gen Prawit are likely to stay put.
Gen Thirachai, a stiff top brass, was trusted enough by both Gen Prawit and Gen Prayut to be made the First Army chief in charge of combat military forces during last year's coup.
He was later appointed leader of the NCPO's peace maintaining forces.
Once an army chief, Gen Thirachai is expected to appoint Gen Pisit Sitthisarn, an army special expert and director of the NCPO's reconciliation efforts, as the army chief-of-staff who will automatically become secretary-general of the Internal Security Operations Command (Isoc).
If appointed as expected, he will be in line to become the next army chief to succeed Gen Thirachai.
Gen Pisit, who is due to retire in 2017, has a good chance to win over other candidates including Lt Gen Chalermchai Sitthisat, head of the Special Warfare Command, in next year's selection of army chief because he is also Gen Prawit's close aide.
Lt Gen Theppong Tippayajan, 1st corps commander, meanwhile, is expected to be made First Army chief, placing him in line for the army chief post later. Lt Gen Theppong is one of Gen Prayut's closest aides, the source said.
Maj Gen Apirat Kongsompong, deputy First Army chief, is expected to succeed Lt Gen Theppong as the new 1st corps commander in next year's reshuffle.
He could then be qualified to assume the army chief post in the future as he retires in 2019.
Also, Gen Sommai Kaodeera, chief of staff of the Royal Thai Armed Forces, becomes the new supreme commander, with his retirement due next year.
Gen Surapong Suwanna-at will succeed Gen Sommai and he could be the next supreme commander.
As for the navy, Adm Na Areenij, chief-of-staff, is to be the new navy chief.
His appointment came as a surprise as Adm Narongpol na Bangchang, assistant navy chief, was previously expected to succeed the incumbent navy chief, Adm Kraisorn Jansuwanich.
A source said Adm Narongpol's nomination as chief faced objection from Gen Prawit and several former navy chiefs due to the fact that the navy had never before appointed someone who graduated abroad as its chief.
Adm Narongpol graduated from a naval school in Germany.
Besides, Adm Na and several of his friends from Class 15 of the AFAPS have close relations with Gen Prawit. Adm Narongpol will serve as deputy navy chief.
Adm Narongpol is in charge of submarine procurement project. The navy plans to purchase three submarines from China for 36 billion baht. The purchase plan now awaits cabinet approval.
In the air force, ACM Jom Rungsawang, chief of staff, is in line to succeed air force chief ACM Treetos Sonjaeng, who retires next year.