The Battle of Bywater was a battle for control of the Shire and the final battle of the War of the Ring.
Background
The Battle was precipitated by Saruman's or Sharkey's take over of The Shire supported by Lotho Sackville-Baggins, and a band of Ruffians
who acted as their enforcers. These events led to major changes in the
shire which were resented by many Hobbits as industrious and
destructive. When the Hobbits Frodo, Merry, Pippin, and Sam
returned to the Shire after their adventures, they did not like what
they saw going on there either. Using the courage and skill they
discovered in themselves while abroad, they were able to take-up
leadership of the Hobbits who wanted to resist the tyranny of Sharkey
and the Ruffians. Soon, the Shire-folk were rallied against the invaders
and managed to assemble a force.Gathering Hobbits for Battle
Upon arriving in Bywater, Frodo, Sam, Merry and Pippin were questioned by the Ruffian Leader as to their intentions. After he had insulted Frodo, the Leaders challenge of authority was met by Pippin, who declared himself as a messenger of the King, and drew his sword against him, Sam and Merry followed suit. The Leader and his men fled, leaving the four hobbits to raise the Shire, and to rally their troops. Merry used the Horn of Rohan to great effect, his call was met by many hobbits throughout that part of the Shire.
The Battle
After returning, then being surrounded by a ring of hobbits, the
Leader, now with more men, was pierced by four hobbit arrows as he
attempted to break away and maim Merry. He died instantly. His gang was
then rounded up and locked away. More Ruffians had been sent by Sharkey
to suppress the Hobbit revolt breaking out in Bywater. However, the
Hobbits scouts gave them advanced warning. The Hobbits then devised a
plan to surround and trap the Ruffians when they arrived. Makeshift
mobile roadblocks were made out of carts and wagons, and after the
Ruffians reached the center of the town the road was blocked in front
and behind them. The Ruffians then tried to fight their way out through
the Hobbits, some breaking through. These were then encircled and
engaged until the battle was won.
The Hobbits were informally commanded by Merry and Pippin. Technically, Pippin was still a Knight of Gondor, as King Elessar had not released him from service but granted him indefinite leave, and when he departed Aragorn reminded Pippin that his restored kingship now extended to the old northern lands which included the Shire. Therefore, Pippin loosely saw himself as fighting off the Ruffians with the authority of the King supporting him. Sam Gamgee also fought in the battle. Frodo was also present at the battle, though he did not fight: he spent the battle making sure that no Ruffians who threw down their weapons were killed as well as making sure that none of the hobbits who had joined the Ruffians were killed stating that no hobbit had killed another hobbit and that it was not going to start there.